signicance of test for petroleum AST

Petroleum Products
Signifi cance of Tests for
8
th
Edition
Signifi cance of Tests for Petroleum Products: 8
th
Edition
Rand
Salvatore J. Rand, Ph.D.
Editor
Dr. Salvatore J. Rand is an independent consultant to the
petroleum industry, and a Fellow of ASTM International.
He was awarded the baccalaureate degree in Chemistry
and Philosophy from Fordham University and a doctorate
in Physical Chemistry and Physics from Rensselaer
Polytechnic Institute. He retired from the Texaco Research
Center following twenty-seven years of service. During
that time he managed the Fuels Test Laboratory, and
provided technical information and services to company
facilities worldwide regarding fuel distribution, marketing
and operations, laboratory inspection and auditing, and
training of personnel both in proprietary and commercial
laboratories. He also represented Texaco on various ASTM
D02 subcommittees. His achievements include developing
company-wide quality control programs for the distribution
of fuels throughout the entire United States.
He has developed and conducts the ASTM training courses
Salvatore J. Rand, Ph.D.
www.astm.org
ISBN: 978-0-8031-7001-8

Stock #: MNL1-8TH
“Gasoline: Speci cations, Testing and Technology” and
“Fuels Technology” and has taught these courses almost
one hundred times throughout the world. He previously
held the position of Second Vice-Chairman of ASTM
Committee D02, Petroleum Products and Lubricants. He
was also Chairman of Subcommittee D02.05, Properties
of Fuels, Petroleum Coke and Carbon Material, Secretary
of Subcommittee D02.05.0C, Color and Reactivity, and a
member of ASTM’s Committee on Technical Committee
Operations (COTCO). He is the author of a number of
publications in the scienti c literature, is a   y year member
of the American Chemical Society, and is a past Chairman
of its Mid-Hudson Section. He is the recipient of numerous
awards, including ASTM’s highest award, the Award of
Merit, D02’s highest award, the Scroll of Achievement, the
George K. Dyro Award of Honorary D02 Membership,
and the Lowrie B. Sargent Award.
ASTM INTERNATIONAL
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Significance of Tests for Petroleum
Products
8th Edition
Salvatore J. Rand, Editor

ASTM Stock Number MNL1-8
TH
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Library of Congress Cataloging-in-Publication Data
Significance of tests for petroleum products. — 8th ed. / [edited by] Salvatore J. Rand.
p. cm.
ISBN 978-0-8031-7001-8
1. Petroleum—Testing. 2. Petroleum products—Testing. I. Rand, Salvatore J., 1933–
TP691.M36 2009
665.5
0
38—dc22 2010003804
Copyright ª 2010 ASTM International, West Conshohocken, PA. All rights reserved. This material may not be repro-
duced or copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage
media, without the written consent of the publisher.
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does not endorse any products represented in this publication.
Printed in Newburyport, MA,
ii
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Foreword
THIS PUBLICATION, Significance of Tests for Petroleum Products: 8
th
Edition, was sponsored by ASTM
committee D02 on Petroleum Products and Lubricants. The editor is Salvatore J. Rand, Consultant, North
Fort Myers, Florida. This is the 8
th
edition of Manual 1 in the ASTM International manual series.
iii

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Dedication
To Mary, Cathy, Jeanne, Joseph, and John
iv

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Acknowledgments

This manual was brought to fruition by the combined efforts of many individuals. I would like to convey
my sincerest appreciation to all of them, particularly the publication staff of ASTM International, espe-
cially Kathy Dernoga and Monica Siperko, who have given us much behind-the-scenes guidance and assis-
tance from the outset of this venture. I also wish to thank Christine Urso of the American Institute of
Physics, who was responsible for this logistically challenging project of handling the 24 chapters and 37
authors involved in this publication. In addition, I wish to convey my accolades to the authors, who are all
experts in their particular fields and who bring a broad spectrum of topics and interests to this manual.
They have devoted considerable time, energy, and resources to support this endeavor. I am also grateful to
the 46 experts who reviewed the various chapters, who through their perusal of the chapters and their sug-
gestions permitted good manuscripts to be made better. Finally, I would like to extend my appreciation to
the industrial and governmental employers of all those involved in this publication. They ultimately make
it possible for us to produce manuals such as this for the benefit of those who use petroleum standards
worldwide.
v

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Contents
Chapter 1—Introduction 1
by Salvatore J. Rand
Chapter 2—Automotive Spark-Ignition Engine Fuel 3

by Lewis M. Gibbs, Ben R. Bonazza, and Robert L. Furey
Chapter 3—Fuel Oxygenates . 16
by Marilyn J. Herman and Lewis M. Gibbs
Chapter 4—Fuels for Land and Marine Diesel Engines and for Nonaviation Gas Turbines 33
by Steven R. Westbrook and Richard T. LeCren
Chapter 5—Biodiesel 53
by Steve Howell
Chapter 6—Burner, Heating, and Lighting Fuels . . 65
by C. J. Martin and Lindsey Hicks
Chapter 7—Aviation Fuels . . . 80
by John Rhode
Chapter 8—Crude Oils 106
by Harry N. Giles
Chapter 9—Properties of Petroleum Coke, Pitch, and Manufactured Carbon and Graphite 123
by C. O. Mills and F. A. Iannuzzi
Chapter 10—Sampling Techniques 136
by Peter W. Kosewicz, Del J. Major, and Dan Comstock
Chapter 11—Methods for Assessing Stability and Cleanliness of Liquid Fuels . 151
by David R. Forester and Harry N. Giles
Chapter 12—Gaseous Fuels and Light Hydrocarbons [Methane through Butanes, Natural Gasoline,
and Light Olefins] 164
by Andy Pickard
Chapter 13—Petroleum Solvents 173
by R. G. Montemayor
Chapter 14—White Mineral Oils 184
by C. Monroe Copeland
Chapter 15—Lubricant Base Oils 189
by Jennifer D. Hall
Chapter 16—Lubricating Oils . 197
by Dave Wills

Chapter 17—Passenger Car Engine Oil and Performance Testing . . . 210
by Raj Shah and Theodore Selby
Chapter 18—Petroleum Oils for Rubber 224
by John M. Long and John H. Bachmann
Chapter 19—Lubricating Greases 229
by Raj Shah
Chapter 20—Petroleum Waxes Including Petrolatums 252
by Alan R. Case
Chapter 21—Methods for the Environmental Testing of Petroleum Products . . 261
by Mark L. Hinman
Chapter 22—Determination of Inorganic Species in Petroleum Products and Lubricants 283
by R. A. Kishore Nadkarni
Chapter 23—Standard Test Method Data Quality Assurance 299
by Alex T. C. Lau
Chapter 24—Synthetic Liquid Fuels . . . 304
by Lelani Collier, Carl Viljoen, Mirriam Ajam, Mazwi Ndlovu, Debby Yoell,
Paul Gravett, and Nico Esterhuyse
Index 316
vii

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1
Introduction
Salvatore J. Rand
1
TECHNOLOGY IS UNDERGOING ACCELERATING
change. No longer do people have to wait months or even
years for analytical methods to be submitted to ASTM Inter-
national, tested, and voted for approval. The response of the
various committees of ASTM International to new develop-
ments in the industrial and petroleum industries, and to
unexpected occurrences in the field, is both swift and
focused. It is because of this unprecedented and exponential
increase in new testing methods that Manual 1 is being
revised only 6 years after its prior publication.
Committee D02 on Petroleum Products and Lubricants
has assumed the responsibility of revising Manual on Signifi-
cance of Tests for Petroleum Products (ASTM Manual Series:
MNL 1), although other national and international standards
organizations contribute significantly to the development of
standard test methods for petroleum products. These organi-
zations include the Energy Institute (EI), formerly known
as the Institute of Petroleum in the United Kingdom, the
Deutsches Institut fu
¨
r Normung (DIN) in Germany, the Asso-
ciation Française de Normalisation (AFNOR) in France, the
Japanese Industrial Standards (JIS) in Japan, the CEN (Euro-
pean Committee for Standardization), and the International
Organization for Standardization (ISO). Selected test meth-

ods from these organizations have been cross-referenced
where relevant with ASTM International standards in selected
chapters in this publication. There are discussions presently
in progress to harmonize many standard test methods so they
are technically equivalent to one another.
The chapters in this manual are not intended to be
research papers or exhaustive treatises of a particular field.
The purpose of the discussions herein is to answer two ques-
tions: What are the relevant tests that are done on various
petroleum products and why do we perform these particular
tests? All tests are designed to measure properties of a prod-
uct such that the “quality” of that product may be described.
I consider a workable definition of a quality product to be
“that which meets agreed-on specifications.” It is not neces-
sary that the quality of a product be judged by its high
purity, although it may very well be, but merely that it meets
specifications previously agreed on among buyers, sellers,
regulators, transferors, etc. The various chapters in this pub-
lication discuss individual or classes of petroleum products
and describe the standardized testing that must be done on
those products to assure all parties involved that they are
dealing with quality products.
Since publication of the previous edition of the manual,
not only has the number available but also the type of some
petroleum products undergone dramatic changes. The result
is that most products have had changes incorporated into
their methods of test, and that these new procedures have
been standardized and a ccepted into specifications a s r equired.
The generic petroleum products discussed in this eighth edi-
tion of Manual 1 are similar to those products described in

the chapters of the previous edition. All chapters with one
exception h ave been updated to reflect new s pecification and
testing standards, w here applicable. Chapter 21, “Methods for
the Environmental Testing of Petroleum Products,” has been
reprinted in its entirety from the previous edition because
the test procedures and protocols have been essentially
unchanged and the discussion of t oxicity a nd biodegradati on
of petroleum p rodu cts i s r elevant t o t oday’s products. In t he
discussion of s ome of the various petroleu m produ cts,
selected sections of chapters have been retained from the
seventh edition for the sake of completeness and to provide
more complete background information. The authors of the
chapters in the seventh edition have been credited in the
footnotes t o the app ropriate chapters w here necessary.
This edition has been enlarged by the inclusion of three
new chapters to more fully reflect today’s new products and
new testing procedures, while the original 21 chapters con-
tained in the seventh edition have been retained and
updated. One new chapter, “Biodiesel,” has been added in
response to the worldwide interest in developing renewable
fuels. In addition to oxygenates, which are generally blended
for gasoline engines, specifications for diesel fuel are being
changed to incorporate materials of biological origin for the
purpose of sustainability of fuels products. Government regu-
lators are mandating the use of biodiesel fuels (“biodiesels”)
and are presently in discussions with petroleum companies
and engine manufacturers to ensure conformance with pub-
lished timetables for the use of these fuels. Committee D02
has responded with the development of specifications and
new test methods, as described in this new chapter.

Another new chapter is entitled “Synthetic Liquid Fuels.”
Again, due to the worldwide interest in diminishing depen-
dence on traditional petroleum fuels, research in alternative
fuels is being conducted by many organizations including
petroleum companies. Specifications and test methods for
synthetic fuels are continually being developed by Committee
D02 to define the characteristics of these new materials, and
these are discussed in the new chapter.
The various petroleum products, including crude oils,
have always been tested to determine the qualitative and
quantitative nature of inorganic substances contained therein.
This is discussed in the new chapter “Determination of
Inorganic Species in Petroleum Products and Lubricants.”
The techniques used are many and varied, the product and
the nature and concentration of the inorganic species. In
1
Consultant, North Fort Myers, FL.
1
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addition, a number of unexpected problems have recently
arisen in the field regarding inorganic materials affecting the
performance of petroleum fuels. One such problem is the
deposition of silicon dioxide on gasoline engine parts due to
the contamination of gasoline with very small quantities of
silicon. Another problem is the inactivation of silver alloy–
sensing units in fuel tanks with the use of some low-sulfur
gasoline fuels. Still another concern is the deposition of
sulfate-containing materials in fuel metering systems and on
fuel dispenser filters when certain ethanol batches a re
blended with gasoline. These problems require methods that
measure inorganic contaminants at extremely low levels using
new techniques, all of which are under development in Com-
mittee D02.
Many of the test procedures described in this manual are
newer correlative methods, which represent the way of the
future due to their simplicity, objectivity, economy, and, in
many cases, portability. Quality assurance methods must be
integrated into analytical procedures and protocols, so that we
can demonstrate that these methods provide accuracy and pre-
cision equal to or better than the referee methods they super-
sede. A major thrust in analytical chemistry at the present is
the development of methods that count individual molecules.
While we have not yet achieved this level of sensitivity in the
testing of petroleum products, when these new tools do arrive,
and they will, we will be able to determine the concentration
of an analyte in a petroleum product with 100% accuracy.
The chapters that follow show that the technology asso-

ciated with the testing of petroleum products is advancing at
an increasingly rapid rate. They also demonstrate that ASTM
International continues to be the foremost standardization
organization in the world.
2 SIGNIFICANCE OF TESTS FOR PETROLEUM PRODUCTS
n 8TH EDITION
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2
Automotive Spark-Ignition Engine Fuel
Lewis M. Gibbs,
1
Ben R. Bonazza,
2
and Robert L. Furey
3
AUTOMOTIVE SPARK-IGNITION ENGINE FUEL
consists of gasoline or gasoline-oxygenate blends used in
internal combustion spark-ignition engines, as opposed to
engine fuels used in diesel or compression-ignition engines.
These spark-ignition engine fuels are used primarily in pas-
senger car and highway truck service. They are also used in
off-highway utility trucks, farm machinery, two- and four-
stroke cycle marine engines, and other spark-ignition engines
used in a variety of service applications.

ASTM D4814, Specification for Automotive Spark-
Ignition Engine Fuel, defines gasoline as a volatile mixture of
liquid hydrocarbons, containing small amounts of additives.
A gasoline-oxygenate blend is defined as a fuel consisting pri-
marily of gasoline, along with a substantial amount of one or
more oxygenates. An oxygenate is an oxygen-containing, ash-
less organic compound, such as an alcohol or ether, which
can be used as a fuel or fuel supplement. Ethanol is the pre-
dominant oxygenate in use today. Spark-ignition engine fuel
includes both gasolines and gasoline-oxygenate blends.
Gasoline is a complex mixture of relatively volatile hydrocar-
bons that vary widely in their physical and chem ical properties.
It is a blend of many hydr ocarbon s derived from the f ractional
distillation of crude petroleum and from complex refinery proc-
esses that increase either the amount or the quality of gasoline.
The hundreds of individual hydrocarbons in gasoline typ-
ically range from those having just four carbon atoms (desig-
nated C
4
, composed of butanes and butenes) to those having
as many as 11 carbon atoms (designated C
11
, such as methyl-
naphthalene). The types of hydrocarbons in gasoline are par-
affins, isoparaffins, naphthenes, olefins, and aromatics. The
properties of commercial gasolines are predominantly influ-
enced by the refinery practices that are used and partially
influenced by the nature of the crude oils from which they
are produced. Finished gasolines have a boiling range from
about 30 to 225°C (86 to 437°F) in a standard distillation test.

Gasoline may be blended, or may be required to be
blended, with oxygenates to improve the octane rating, extend
the fuel supply, reduce vehicle exhaust emissions, or comply
with regulatory requirements. The oxygenated components of
spark-ignition engine fuel include aliphatic ethers, such as
methyl tert-butyl ether (MTBE), and alcohols such as ethanol.
The ethers are allowed by U.S. Environmental Protection
Agency (EPA) regulations to be used in concentrations where
they provide not more than 2.7 mass percent oxygen in the final
fuel blend. Because of concerns over ground water contamina-
tion, MTBE is banned in many sta tes a nd is no longer wi d ely
used in the United States. Ethanol and certain other alcohols
may provide not more than 3.7 mass percent oxygen in the fuel.
Legal restrictions exist on the use of methanol in gasoline, and
it is not currently intentionally added to any gasolines marketed
in the United States. These restrictions will be di scussed later.
The federal Renewable Fuel Standard (RFS) established under
the En ergy Independence and Security Act of 2 007 requires a
national minimum volume usage requirement of ethanol that
increases annually until 2022. In addition, a number of states or
portions of states mandate that spark-ignition engine fuel con-
tain 10 volume percent ethanol blended with gasoline.
Spark-ignition engine fuels are blended to satisfy diverse
automotive requirements. In addition, the fuels are exposed
to a variety of mechanical, physical, and chemical environ-
ments. Therefore, the properties of the fuel must be bal-
anced to give satisfactory engine performance over an
extremely wide range of operating conditions. The prevailing
standards for fuel represent compromises among the numer-
ous quality, environmental, and performance requirements.

Antiknock rating, distillation characteristics, vapor pressure,
sulfur content, oxidation stability, corrosion protection, and
other properties are balanced to provide satisfactory vehicle
performance. In most gasolines, additives are used to pro-
vide or enhance specific performance features.
In recent years, there has been an ever-growing body of gov-
ernmental regulations to address concerns a bout the environ-
ment. Initially, most of the regulations were aimed at the
automobile and h ave resulted i n technologies that have signifi-
cantly reduced vehicle emissions. Regulations have also been
aimed at compositional changes to the fuels that result in
reduced vehicle emissions. The first major change in fuel compo-
sition was the introduction of unleaded gasoline in the early
1970s, followed by the phase-down of lead levels in lead ed gaso-
line (1979–1986). Most passenger cars and light-duty trucks
beginning with the 1975 model yearhaverequiredunleadedfuel.
In 1989, the U.S. EPA implemented gasoline volatility
regulations. Reductions in fuel vapor pressure limits during
the summer were implemented under these regulations, fol-
lowed by further reductions in 1992.
Beginning in 1987, several states required the addition
of oxygenates to gasoline during the winter months in cer-
tain geographic areas to reduce vehicle carbon monoxide
emissions. The added oxygenates are especially effective in
reducing carbon monoxide during a cold start with older
vehicles. When a vehicle is started cold, the catalyst is inac-
tive and the computer is not controlling the air-fuel ratio in
closed-loop mode. Added oxygen in the fuel leans the
vehicle’s fuel mixture, lowering carbon monoxide emissions.
The Clean Air Act Amendments of 1990 required addi-

tional compositional changes to automotive spark-ignition
1
Chevron Products Company, Richmond, CA.
2
TI Automotive (retired), Lapeer, MI.
3
Furey & Associates, LLC, Rochester Hills, MI.
3
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engine fuels. In November 1992, 39 areas failing to meet the
federal standard for carbon monoxide were required to
implement oxygenated fuel programs similar to those men-
tioned previously. There are also provisions in the act that
address ozone nonattainment. Beginning in 1995, the use of
a cleaner-burning “reformulated gasoline” was required in
the nine worst ozone nonattainment areas. Other ozone non-
attainment areas have the option of participating in the pro-

gram. Federal reformulated gasoline is a gasoline-oxygenate
blend certified to meet the specifications and emission
reduction requirements established by the Clean Air Act
Amendments of 1990; therefore, it would be more correctly
referred to as federal reformulated spark-ignition engine
fuel. Federal and state regulations frequently use the term
“gasoline” to cover both gasoline and gasoline-oxygenate
blends. (See ASTM Committee D0 2 on Petroleum Products
and Lubricants Rese arch Report D02: 1347, Research
Report on Reformulated Spark-Ignition Engine Fuel for
reformulated gasoline requirements and test methods.)
This chapter summarizes the significance of the more
important physical and chemical characteristics of automo-
tive spark-ignition engine fuel and describes pertinent test
methods for defining or evaluating these properties. Infor-
mation on governmental requirements is also provided. This
discussion applies only to those fuels that can be used in
engines designed for spark-ignition engine fuel. It does not
include fuels that are primarily oxygenates, such as M85, a
blend of 85 volume percent methanol and 15 volume per-
cent gasoline, or E85, a blend of 85 volume percent ethanol
and 15 volume percent gasoline, which are for use in flexi-
ble fuel vehicles. These fuels and the oxygenates commonly
used in gasoline are discussed in detail in Chapter 3. [See
ASTM D5797, Specification for Fuel Methanol (M70-M85) for
Automotive Spark-Ignition Engines, or ASTM D5798, Specifi-
cation for Fuel Ethanol (Ed75-Ed85) for Automotive Spark-
Ignition Engines.]
GRADES OF SPARK-IGNITION ENGINE FUEL
Until 1970, with the exception of one brand of premium-

grade fuel marketed on the East Coast and southern areas
of the United States, all grades of automotive fuel contained
lead alkyl compounds to increase the antiknock rating. The
Antiknock Index [the average of the Research Octane Num-
ber (RON) and the Motor Octane Number (MON)] of the
leaded premium-grade fuel pool increased steadily from
about 82 at the end of World War II to about 96 in 1968.
During the same time, the Antiknock Index of the leaded
regular grade followed a parallel trend from about 77 to 90.
Leaded fuel began to be phased out during the 1970s, and
in 1996 all lead was banned from highway fuel.
In 1971, U.S. passenger car manufacturers began a tran-
sition to engines that would operate satisfactorily on fuels
with lower octane ratings, namely, a minimum RON of 91.
This octane level was chosen because unleaded fuels are
needed to prolong the effectiveness of automotive emission
catalyst systems and because unleaded fuels of 91 RON could
be produced in the required quantities using refinery process-
ing equipment then available. In 1970, fuel marketers intro-
duced unleaded and low-lead fuels of this octane level to
supplement the conventional leaded fuels already available.
Beginning in July 1974, the U.S. EPA mandated that
most service stations have available a grade of unleaded fuel
defined as having a lead content not exceeding 0.013 gram of
lead/liter (g Pb/L) [0.05 gram of lead/U.S. gallon (0.05 g Pb/
gal)] and a RON of at least 91. (This was changed to a mini-
mum Antiknock Index of 87 in 1983, and the requirement
was dropped in 1991.) Starting in the 1975 model year, most
spark-ignition engine–powered automobiles and light-duty
trucks required the use of unleaded fuel. With this require-

ment, low-lead fuels [0.13 g Pb/L (0.5 g Pb/gal)] disappeared.
In addition, leaded premium began to be superseded by
unleaded premium in the late 1970s and early 1980s. In the
mid-1980s, an unleaded midgrade fuel became widely avail-
able, and many fuel marketers now offer three grades of
unleaded fuel: regular, midgrade, and premium. Lead usage
in motor fuels was banned entirely in California effective in
1992 and was banned from all U.S. reformulated fuels in
1995 and from all U.S. motor fuels in 1996. Leaded fuel can
still be produced for off-road use and for use as a racing fuel.
ANTIKNOCK RATING
The definitions and test methods for antiknock rating for
automotive spark-ignition engine fuels are set forth in Appen-
dix X1 in ASTM D4814, Specification for Automotive Spark-
Ignition Engine Fuel. Antiknock rating and volatility are per-
haps the two most important characteristics of spark-ignition
engine fuel. If the antiknock rating of the fuel is lower than
that required by the engine, knock occurs. Knock is a high-
pitch, metallic rapping noise. Fuel with an antiknock rating
higher than that required for knock-free operation generally
does not improve performance. However, vehicles equipped
with knock sensors may show a performance improvement
as the antiknock rating of the fuel is increased, provided that
the antiknock rating of the fuel is lower than that required
by the engine. Conversely, reductions in fuel antiknock rat-
ing may cause a loss in vehicle performance. The loss of
power and the damage to an automotive engine due to
knocking are generally not significant until the knock inten-
sity becomes severe and prolonged.
Knock depends on complex physical and chemical phe-

nomena highly interrelated with engine design and operat-
ing conditions. It has not been possible to characterize
completely the antiknock performance of spark-ignition
engine fuel with any single measurement. The antiknock per-
formance of a fuel is related intimately to the engine in
which it is used and the engine operating conditions. Fur-
thermore, this relationship varies from one engine design to
another and may even be different among engines of the
same design, due to normal production variations.
The antiknock rating of a spark-ignition engine fuel is
measured in single-cylinder laboratory engines. Two methods
have been standardized and are presented in ASTM D2699/
IP 237, Test Method for Research Octane Number of Spark-
Ignition Engine Fuel, and ASTM D2700/IP 236, Test Method
for Motor Octane Number of Spark-Ignition Engine Fuel.
Another method used for quality control in fuel blending is
given in ASTM D2885/IP 360, Test Method for Research and
Motor Method Octane Ratings Using On-Line Analyzers.
These single-cylinder engine test procedures use a variable-
compression-ratio engine. The Motor method operates at a
higher speed and inlet mixture temperature than the Research
method. The procedures relate the knocking characteristics of
a test fuel to standard fuels, which are blends of two pure
hydrocarbons: 2,2,4-trimethylpentane (“isooctane”) and
n-heptane. These blends are called primary reference fuels.By
definition, the octane number of isooctane is 100, and the
4 SIGNIFICANCE OF TESTS FOR PETROLEUM PRODUCTS
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octane number of n-heptane is 0. At octane levels below 100,
the octane number of a given fuel is the percentage by volume
of isooctane in a blend with n-heptane that knocks with the
same intensity at the same compression ratio as the fuel when
compared by one of the standardized engine test methods. The
octane number of a fuel greater than 100 is based on the vol-
ume of tetraethyl lead that must be added to isooctane to pro-
duce knock with the same intensity as the fuel. The volume of
tetraethyl lead in isooctane is converted to octane numbers
greater than 100 by use of tables included in the Research and
Motor methods.
The octane number of a given blend of either isooctane
and n-heptane or tetraethyl lead in isooctane is, by definition,
the same for the Research and Motor methods. However, the
RON and MON will rarely be the same for commercial fuels.
Therefore, when considering the octane number of a given
fuel, it is necessary to know the engine test method. RON
is, in general, the better indicator of antiknock rating for
engines operating at full throttle and low engine speed. MON
is the better indicator at full throttle, high engine speed, and
part throttle, low and high engine speed. The difference
between RON and MON is called “sensitivity.” According to
recent surveys of U.S. commercial fuels, the average sensitiv-
ity is about 9 units for unleaded regular grade and about 10
units for unleaded premium grade.
For most automotive engines and operating conditions,

the antiknock performance of a fuel will be between its RON
and MON. The exact relationship is dependent on the vehicle
and operating conditions. Antiknock Index [the average of
RON and MON, that is, (R þ M)/2] is a currently accepted
method of relating RON and MON to actual road antiknock
performance in vehicles. U.S. Federal Trade Commission
(FTC) regulations require a label on each service station dis-
pensing pump showing the minimum (R þ M)/2 value of the
fuel dispensed. For fuels sold in the United States, regular
grade is typically 87 (R þ M)/2 (often slightly lower at high alti-
tudes), midgrade is typically about 89, and premium is typi-
cally 91 or higher. Other grades also exist. The terms used to
describe the various grades (e.g., regular, midgrade, super, pre-
mium, etc.) vary among fuel marketers and location. With the
FTC regulation, a consumer can match the (Rþ M)/2 value
specified in the owner’s manual with the value on the pump.
Because octane quality is a marketing issue, ASTM does not
specify a minimum Antiknock Index in ASTM D4814.
VOLATILITY
The volatility characteristics of a spark-ignition engine fuel
are of prime importance to the driveability of vehicles under
all conditions encountered in normal service. The large var-
iations in operating conditions and wide ranges of atmos-
pheric temperatures and pressures impose many limitations
on a fuel if it is to give satisfactory vehicle performance.
Fuels that vaporize too readily in pumps, fuel lines, carburet-
ors, or fuel injectors will cause decreased fuel flow to the
engine, resulting in hard starting, rough engine operation, or
stoppage (vapor lock). Under certain atmospheric condi-
tions, fuels that vaporize too readily can also cause ice for-

mation in the throat of a carburetor, resulting in rough idle
and stalling. This problem occurs primarily in older cars.
Conversely, fuels that do not vaporize readily enough may
cause hard starting and poor warm-up driveability and accel-
eration. These low-volatility fuels may also cause an unequal
distribution of fuel to the individual cylinders.
The volatility of automotive spark-ignition engine fuel
must be carefully “balanced” to provide the optimum com-
promise among performance features that depend on the
vaporization behavior. Superior performance in one respect
may give serious trouble in another. Therefore, volatility
characteristics of automotive fuel must be adjusted for sea-
sonal variations in atmospheric temperatures and geographic
variations in altitude. Four common volatility properties are
described later. The effect of these volatility parameters on
the performance of the vehicle is also presented.
Vapor Pressure
One of the most common measures of fuel volatility is the
vapor pressure at 37.8°C (100°F) measured in a chamber
having a 4:1 ratio of air to liquid fuel. ASTM D323, Test
Method for Vapor Pressure of Petroleum Products (Reid
Method), can be used for hydrocarbon-only gasolines and
gasoline-ether blends but not for gasoline-alcohol blends
because traces of water in the apparatus can extract the
alcohol from the blend and lead to incorrect results. There-
fore, this method is no longer listed as an acceptable test
method for spark-ignition engine fuels in ASTM D4814.
To avoid the alcohol–water interaction problem in Test
Method D323, a similar method using the same apparatus
and procedure, but maintaining dry conditions, has been

developed—ASTM D4953, Test Method for Vapor Pressure of
Gasoline and Gasoline-Oxygenate Blends (Dry Method). The
results are reported as Dry Vapor Pressure Equivalent
(DVPE) rather than Reid Vapor Pressure (RVP), which is only
determined using Test Method D323. For hydrocarbon-only
gasolines, there is no statistically significant difference in the
results obtained by Test Methods D323 and D4953. Advances
in instrumentation have led to the development of three
other methods that can be used for both gasolines and gaso-
line-oxygenate blends. They are ASTM D5190, Test Method
for Vapor Pressure of Petroleum Products (Automatic Method),
ASTM D5191, Test Method for Vapor Pressure of Petroleum
Products (Mini Method), and ASTM D5482, Test Method
for Vapor Pressure of Petroleum Products (Mini Method-
Atmospheric). The precision (repeatability and reproducibil-
ity) of these three methods is much better than that for
D4953. Another method, ASTM D6378, Test Method for
Determination of Vapor Pressure (VP
X
) of Petroleum Prod-
ucts, Hydrocarbons, and Hydrocarbon-Oxygenate Mixtures
(Triple Expansion Method), is reported to not require air sat-
uration and cooling of the sample before testing. This test
method reports results as VP
X
. An equation is provided in
the test method to convert the results to DVPE to determine
compliance with Specification D4814 maximum limits.
The U.S. EPA and the California Air Resources Board
use the D5191 test method. However, each uses a slightly dif-

ferent equation than that used by ASTM to calculate vapor
pressure from the instrument’s total pressure reading. The
equation used depends on the brand of the instrument.
Distillation
The tendency of a fuel to vaporize is also characterized by
determining a series of temperatures at which various per-
centages of the fuel have evaporated, as described in ASTM
D86, Test Method for Distillation of Petroleum Products at
Atmospheric Pressure. A plot of the results is commonly
called the distillation curve. The 10, 50, and 90 volume per-
cent evaporated temperatures are often used to characterize
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the volatility of spark-ignition engine fuel. The fuel also can
be characterized by reporting the percentage evaporated at
specified temperatures (e.g., E100). Two gas chromatography
test methods that can be used to determine the distillation
characteristics are ASTM D3710, Test Method for Boiling
Range Distribution of Gasoline and Gasoline Fractions by
Gas Chromatography, and D7096, Test Method for Determi-
nation of the Boiling Range Distribution of Gasoline by
Wide-Bore Capillary Gas Chromatography. Two distillation
test methods requiring considerably smaller sample sizes
than Test Method D86 are D7344, Test Method for Distilla-

tion of Petroleum Products at Atmospheric Pressure (Mini
Method), and D7345, Test Method for Distillation of Petro-
leum Products at Atmospheric Pressure (Micro Distillation
Method). To improve the correlation of reported results with
those of Test Method D86, bias corrections are provided.
Driveability Index
While each area of the distillation curve is important, the
combination of the various points that describe the whole
curve must be taken into account to describe adequately vehi-
cle driveability. The ASTM Driveability Task Force, using data
from the Coordinating Research Council (CRC) and others,
has developed a correlation between various distillation
points and vehicle cold-start and warm-up driveability. This
correlation is called Driveability Index (DI) and is defined as:
DI ¼ 1.5
3 T
10
þ 3.0 3 T
50
þ 1.0 3 T
90
þ 1.33°C(2.4°F)
3 Ethanol Volume percent, where T
10
,T
50
,andT
90
are the
temperatures at the 10, 50, and 90 % evaporated points of a

Test Method D86 distillation, respectively; 1.33 is the coeffi-
cient for the volume percent ethanol present when the distil-
lation results are determined in degrees Celsius; and 2.4 is
the coefficient when distillation results are determined in
degrees Fahrenheit. The ethanol correction term is required
because the reduction in the T
50
resulting from the addition
of ethanol does not provide as much improvement in drive-
ability as would such a reduction by a hydrocarbon.
Vapor-Liquid Ratio
The vaporization tendency of spark-ignition engine fuel can
also be expressed in terms of vapor-to-liquid ratio (V/L) at
temperatures approximating those found in critical parts of
the fuel system. The standard test method is ASTM D5188,
Test Method for Vapor-Liquid Ratio Temperature Determina-
tion of Fuels (Evacuated Chamber Method). This method is
applicable to samples for which the determined temperature
is between 36 and 80°C and the V/L is between 8:1 and 75:1.
The fuel temperature at a V/L o f approximately 20
(T
V/L¼20
) was shown to be indicative of the tendency of a
fuel to cause vapor lock, as evidenced by loss of power dur-
ing full-throttle accelerations. V/L–temperature relationships
were originally developed for vehicles equipped with carbu-
retors and suction-type fuel pumps. The applicability of such
relationships to late-model vehicles equipped with fuel injec-
tion and pressurized fuel systems has been shown by CRC
test programs. Appendix X2 of ASTM D4814 includes a com-

puter method and a linear equation method that can be
used for estimating V/L of spark-ignition engine fuels from
vapor pressure and distillation test results. However, until
recently these estimation methods were not applicable to
gasoline-oxygenate blends. ASTM D4814 in Appendix X2 now
provides equations for correcting the estimated values appli-
cable to ethanol blends.
Volatility and Performance
In general terms, the following relationships between volatil-
ity and performance apply:
1. High vapor pressures and low 10 % evaporated tempera-
tures are both conducive to ease of cold starting. How-
ever, under hot operating conditions, they are also
conducive to vapor lock and increased vapor formation
in fuel tanks, carburetors, and fuel injectors. The amount
of vapor formed in fuel tanks and carburetors, which
must be contained by the evaporative emissions control
system, is related to the vapor pressure and distillation
temperatures. Thus, a proper balance of vapor pressure
and 10 % evaporated temperature must be maintained
and seasonally adjusted for good overall performance.
2. Although vapor pressure is a factor in the amount of
vapor formed under vapor locking conditions, vapor
pressure alone is not a good index. A better index for
measuring the vapor locking performance of spark-igni-
tion engine fuels is the temperature at which the V/L is
20 at atmospheric pressure. The lower the temperature at
which V/L ¼ 20, the greater is the tendency to cause vapor
lock and hot-fuel–handling driveability problems. Vapor
lock is much less of a problem for fuel-injected cars,

which have pressurized fuel systems. However, driveabil-
ity symptoms are similar to carbureted vehicles; a too-
volatile fuel in fuel-injected cars can cause hard starting
and rough idling, and in the extreme, the car will not start.
3. The distillation temperature at which 50 % of the fuel
has evaporated is a broad indicator of warm-up and
acceleration performance under cold-starting conditions.
The lower the 50 % evaporated temperature, the better
is the performance. (This statement is not always valid
for gasoline-oxygenate blends, especially those contain-
ing alcohol.) The temperatures for 10 and 90 % evapo-
rated are also indicators of warm-up performance under
cold-starting conditions, but to a lesser degree than the
50 % evaporated temperature. Lowering the 50 % evap-
orated point, within limits, also has been shown to
reduce exhaust hydrocarbon emissions.
4. The temperatures for 90 % evaporated and the final boil-
ing point, or end point, indicate the amount of relatively
high-boiling components in gasoline. A high 90 % evapo-
rated temperature, because it is usually associated with
higher density and high-octane number components, may
contribute to improved fuel economy and resistance to
knock. If the 90 % evaporated temperature and the end
point are too high, they can cause poor mixture distribu-
tion in the intake manifold and combustion chambers,
increased hydrocarbon emissions, excessive combustion
chamber deposits, and dilution of the crankcase oil.
5. DI represents the entire distillation curve. Lower values of
DI mean greater volatility, which equates to better cold-
start and warm-up driveability until some minimum level

is reached where no further improvement is observed. If
the DI is too high, vehicle cold-start and warm-up drive-
ability can be adversely affected. Maximum DI for each
volatility class is limited by ASTM D4814 and other specifi-
cations developed by motor vehicle manufacturers and by
fuel suppliers. A DI specification limit allows a refiner
more flexibility in blending spark-ignition engine fuel that
provides proper cold-start and warm-up driveability, com-
pared to tight restrictions on individual distillation points.
As ambient temperature is reduced, fuels with lower DI
6 SIGNIFICANCE OF TESTS FOR PETROLEUM PRODUCTS
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are required. The impact of oxygenates on DI and drive-
ability is not well established. Some testing has shown that
at the same DI level, poorer driveability occurs with oxy-
genated fuels. Other data have not shown this effect. The
oxygenate effect may depend on the ambient tempera-
ture, type of oxygenate, and DI level of the fuel. The DI
equation now contains a correction for ethanol blends.
The CRC continues to investigate this issue.
ASTM D4814, Specification for Automotive Spark-Igni-
tion Engine Fuel, includes a table of six volatility classes for
vapor pressure, distillation temperatures, and DI, and a sepa-
rate vapor lock protection table of six volatility classes for

T
V/L¼20
. A combination of limits from these two tables defines
the fuel volatility requirements for each month and geo-
graphic area of the United States. The specification also
accounts for the EPA regulations on vapor pressure and state
implementation plan (SIP) vapor pressure limits approved by
the EPA. These volatility characteristics have been established
on the basis of broad experience and cooperation between
fuel suppliers and manufacturers and users of automotive
vehicles and equipment. Spark-ignition engine fuels meeting
this specification have usually provided satisfactory perform-
ance in typical passenger car service. However, certain equip-
ment or operating conditions may require or permit
variations from these limits. Modern vehicles, designed to
exacting tolerances for good emission control, fuel economy,
and driveability, may require more restrictive limits.
OTHER PROPERTIES
In addition to providing acceptable antiknock performance
and volatility characteristics, automotive spark-ignition engine
fuels must also provide for satisfactory engine and fuel sys-
tem cleanliness and durability. The following properties have
a direct bearing on the overall performance of a fuel.
Workmanship and Contamination
A finished fuel is expected to be visually free of undissolved
water, sediment, and suspended matter. It should be clear
and bright when observed at 21°C (70°F). It should also be
free of any adulterant or contaminant that may render the
fuel unacceptable for its commonly used applications. Physi-
cal contamination may occur during refining or distribution

of the fuel. Control of such contamination is a matter requir-
ing constant vigilance by refiners, distributors, and market-
ers. Solid and liquid contamination can lead to restriction of
fuel metering orifices, corrosion, fuel line freezing, gel for-
mation, filter plugging, and fuel pump wear. ASTM D2709,
Test Method for Water and Sediment in Distillate Fuels by
Centrifuge, or ASTM D2276/IP 216, Test Method for Particu-
late Contaminant in Aviation Fuel by Line Sampling, can be
used to determine the presence of contaminants. Appendix
X6 of ASTM D4814 contains a recommendation that all fuel
dispensers be equipped with filters of 10-micron (microme-
ter) or less nominal pore size at point of delivery to the
customer.
Petroleum products pick up microbes during refining,
distribution, and storage. Most growth takes place where fuel
and water meet. Therefore, it is most important to minimize
water in storage tanks. Microbial contamination in fuel was
not much of a problem until lead was removed. Appendix
X5 of ASTM D4814 discusses microbial contamination and
references ASTM D6469, Guide for Microbial Contamination
in Fuels and Fuel Systems.
Lead Content
Constraints imposed by emission control regulations and
health concerns have led to the exclusive availability of
unleaded fuels for street and highway use. Leaded fuel is still
allowed for nonroad use, such as for farm equipment and for
racing. The lead content of unleaded fuel is limited to a maxi-
mum of 0.013 g Pb/L (0.05 g Pb/gal), but typical lead contents
in U.S. unleaded fuels are 0.001 g Pb/L or less. Although the
EPA regulations prohibit the deliberate addition of lead to

unleaded fuels, some contamination by small amounts of lead
can occur in the distribution system. Such occurrences are rare,
because leaded fuel has been eliminated from the market.
The following methods are suitable for determining the
concentration of lead in spark-ignition engine fuel:
FOR LEADED FUEL
ASTM D3341, Test Method for Lead in Gasoline–Iodine Mono-
chloride Method
ASTM D5059/IP 228, Test Methods for Lead in Gasoline by
X-Ray Spectroscopy
FOR UNLEADED FUEL
ASTM D3237, Test Method for Lead in Gasoline by Atomic
Absorption Spectroscopy
ASTM D3348, Test Method for Rapid Field Test for Trace
Lead in Unleaded Gasoline (Colorimetric Method)
ASTM D5059/IP 228, Test Methods for Lead in Gasoline by
X-Ray Spectroscopy
Phosphorus Content
In the past, phosphorus compounds were sometimes a dded to
leaded fuels as combustion chamber deposit modifiers. However,
because phosphorus adversely affects exhaust emission control
system components, p articularly t he ca talytic conve rter, today
EPA regulations limit its concentration in unleaded fuel to a max-
imum of 0.0013 g P/L (0.005 g P/gal). Furthermore, phosphorus
may not be intentionally added to unl eaded fuel in any concen-
tration. The concentration of phosphorus can be determined by
ASTM D3231, Test Method for Phosphorus in Gasoline.
Manganese Content
In the 1970s, methylcyclopentadienyl manganese tricarbonyl
(MMT) was added to some unleaded fuels for octane improve-

ment. However, the use of MMT was banned in 1977 in Califor-
nia. In October 1978, the EPA banned its use in unleaded fuel
throughout the United States because it increased vehicle
hydrocarbon emissions in various test programs, including the
63-vehicle CRC program in 1977. In 1995, after much testing
and court action, MMT was granted a waiver by the EPA for
use at a maximum concentration of 0.008 g Mn/L (0.031 g Mn/
gal). According to the EPA’s website, “the Agency determined
that MMT added at 1/32 gpg Mn will not cause or contribute to
regulated emissions failures of vehicles.” Nevertheless, the use
of MMT remains controversial. The EPA’s website notes the
agency’s uncertainty about the health risks of using MMT. The
manganese content of spark-ignition engine fuel can be deter-
mined by ASTM D3831, Test Method for Manganese in Gaso-
line by Atomic Absorption Spectroscopy.
Sulfur Content
Crude petroleum contains sulfur compounds, most of which
are removed during refining. The maximum amount of sul-
fur as specified in ASTM D4814 is 0.0080 mass percent,
CHAPTER 2
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which is the federal per-gallon maximum limit. The federal
regulations also have a refinery annual average maximum
limit of 0.0030 mass percent. There are a few exceptions for

qualified refineries that expire by the end of 2010.
Sulfur oxides formed during combustion may be con-
verted to acids that promote rusting and corrosion of engine
parts and exhaust systems. Sulfur oxides formed in the exhaust
are undesirable atmospheric pollutants. However, the contri-
bution of automotive exhaust to total sulfur oxide emissions is
negligible. Sulfur also reduces the effectiveness of exhaust gas
catalytic converters. In 1996, California set an average maxi-
mum limit of 0.0030 mass percent and then at the end of 2003
lowered it to 0.0015 mass percent. More details on sulfur
requirements are presented later in this chapter.
The sulfur content of spark-ignition engine fuel can be
determined by the following methods:
• ASTM D1266/IP 107, Test Method for Sulfur in Petro-
leum Products (Lamp Method)
• ASTM D2622, Test Method for Sulfur in Petroleum Products
by Wavelength Dispersive X-Ray Fluorescence Spectrometry
• ASTM D3120, Test Method for Trace Quantities of Sulfur in
Light Liquid Hydrocarbons by Oxidative Microcoulometry
• ASTM D4045, Test Method for Sulfur in Petroleum Prod-
ucts by Hydrogenolysis and Rateometric Colorimetry
• ASTM D4294, Test Method for Sulfur in Petroleum and
Petroleum Products by Energy-Dispersive X-Ray Fluores-
cence Spectrometry
• ASTM D5453, Test Method for Determination of Total
Sulfur in Light Hydrocarbons, Spark Ignition Engine
Fuel and Engine Oil by Ultraviolet Fluorescence
• ASTM D6334, Test Method for Sulfur in Gasoline by
Wavelength Dispersive X-Ray Fluorescence
• ASTM D6445, Test Method for Sulfur in Gasoline by

Energy-Dispersive X-Ray Fluorescence Spectrometry
• ASTM D6920, Test Method for Total Sulfur in Naphthas,
Distillates, Reformulated Gasolines, Diesels, Biodiesels,
and Motor Fuel by Oxidative Combustion and Electro-
chemical Detection
• ASTM D7039, Test Method for Sulfur in Gasoline and
Diesel Fuel by Monochromatic Wavelength Dispersive X-
Ray Fluorescence Spectrometry
It is important to review the sulfur content determination
minimum and maximum levels before selecting a test method
to ensure it is applicable for the test sample of interest.
The presence of free sulfur or reactive sulfur compounds
can be detected by ASTM D130/IP 154, Test Method for Detec-
tion of Copper Corrosion from Petroleum Products by the
Copper Strip Tarnish Test, or by ASTM D4952, Test Method
for Qualitative Analysis for Active Sulfur Species in Fuels and
Solvents (Doctor Test). Sulfur in the form of mercaptans can
be determined by ASTM D3227/IP 342, Test Method for (Thiol
Mercaptan) Sulfur in Gasoline, Kerosene, Aviation Turbine,
and Distillate Fuels (Potentiometric Method).
Gum and Stability
During storage, fuels can oxidize slowly in the presence of
air and form undesirable oxidation products such as perox-
ides and/or gum. These products are usually soluble in the
fuel, but the gum may appear as a sticky residue on evapora-
tion. These residues can deposit on carburetor surfaces, fuel
injectors, and intake manifolds, valves, stems, guides, and
ports. ASTM D4814 limits the solvent-washed gum content
of spark-ignition engine fuel to a maximum of 5 mg/100 mL.
ASTM D381/IP 131, Test Method for Gum Content in Fuels

by Jet Evaporation, is used to determine gum content.
Many fuels are deliberately blended with nonvolatile oils
or additives or both, which remain as residues in the evapo-
ration step of the gum test. A heptane-washing step is, there-
fore, a necessary part of the procedure to remove such
materials, so that the solvent washed gum may be deter-
mined. The unwashed gum content (determined before the
heptanes-washing step) indicates the presence of nonvolatile
oils or additives. ASTM Test Method D381/IP 131 also is used
to determine the unwashed gum content. There is no specifi-
cation limit for unwashed gum content in ASTM D4814.
Automotive fuels usually have a very low gum content
when manufactured but may oxidize to form gum during
extended storage. ASTM D525/IP 40, Test Method for Oxidation
Stability of Gasoline (Induction Period Method), is a test to indi-
cate the tendency of a fuel to resist oxidation and gum forma-
tion. It should be recognized, however, that the method’s
correlation with actual field service may vary markedly under
different storage conditions and with different fuel blends. Most
automotive fuels contain special additives (antioxidants) to pre-
vent oxidation and gum formation. Some fuels also contain
metal deactivators for this purpose. Commercial fuels available
in service stations move rather rapidly from refinery produc-
tion to vehicle usage and are not designed for extended storage.
Fuels purchased for severe bulk storage conditions or for pro-
longed storage in vehicle fuel systems generally have additional
amounts of antioxidant and metal deactivator added.
Although not designed for automotive fuel, ASTM D873,
Test Method for Oxidation Stability of Aviation Fuels (Poten-
tial Residue Method), is sometimes used to evaluate the sta-

bility of fuel under severe conditions, and like ASTM D525,
it can indicate the tendency of the fuel to oxidize. No corre-
lation has been established between the results of this test
and actual automotive service, but the comparative rankings
of fuels tested by D873 are often useful.
Peroxides are undesirable in automotive fuel because
they can attack fuel system elastomers and copper commuta-
tors in fuel pumps. Peroxides can participate in an autocata-
lytic reaction to form more peroxides, thus accelerating the
deterioration of fuel system components. Also, peroxides
reduce the octane rating of the fuel. Hydroperoxides and
reactive peroxides can be determined by ASTM D3703, Test
Method for Peroxide Number of Aviation Turbine Fuels, or
by ASTM D6447, Test Method for Hydroperoxide Number of
Aviation Turbine Fuels by Voltammetric Analysis.
Density and Relative Density
ASTM D4814 does not set limits on the density of spark-ignition
engine fuels, because the density is fixed by the other chemical
and physical properties of the fuel. Density relates to the volu-
metric energy content of the fuel—the more dense the fuel, the
higher is the volumetric energy content. Density is important,
also, because fuel is often bought and sold with reference to a
specific temperature, usually 15.6°C(60°F). Because the fuel is
usually not at the specified temperature, volume correction fac-
tors based on the change in density with temperature are used
to correct the volume to that temperature. Volume correction
factors for oxygenates differ somewhat from those for hydro-
carbons, and work is in progress to determine precise correc-
tion factors for gasoline-oxygenate blends.
Rather than using absolute density (in units of kg/m

3
, for
example), relative density is often used. Relative density, or
8 SIGNIFICANCE OF TESTS FOR PETROLEUM PRODUCTS
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specific gravity, is the ratio of the mass of a given volume of
fuel at a given temperature to the mass of an equal volume of
water at the same temperature. Most automotive fuels have
relative densities between 0.70 and 0.78 at 15.6°C (60°F).
The American Petroleum Institute (API) gravity is often
used as a measure of a fuel’s relative density, although this
practice is now discouraged with the move toward the use of
SI units. API gravity is based on an arbitrary hydrometer scale
and is related to specific gravity at 15.6°C(60°F) as follows:
API Gravity; Deg: ¼
141:5
sp grð15:6=15:6

CÞ
À 131:5 ð1Þ
Fuel density is determined by ASTM D1298/IP 160, Test
Method for Density, Relative Density (Specific Gravity), or
API Gravity of Crude Petroleum and Liquid Petroleum Prod-
ucts by Hydrometer Method, or by ASTM D4052/IP 365, Test

Method for Density and Relative Density of Liquids by Digi-
tal Density Meter.
Rust and Corrosion
Filter plugging and engine wear problems are reduced by
minimizing rust and corrosion in fuel distribution and vehi-
cle fuel systems. Modifications of ASTM D665/IP 135, Test
Method for Rust-Preventing Characteristics of Inhibited Min-
eral Oil in the Presence of Water, are sometimes used to
measure rust protection of fuels.
Silver Corrosion
Reactive trace sulfur compounds (elemental sulfur, hydro-
gen sulfide, and mercaptans) present in fuel under some cir-
cumstances can corrode or tarnish silver alloy fuel gage in-
tank sending units, causing them to fail. To minimize the
failure of the silver fuel gage sending units, the fuel must
pass the silver corrosion test method described in Annex A1
in ASTM Specification D4814. The test method uses the
ASTM Test Method D130 test apparatus except a silver cou-
pon replaces the normal copper one. ASTM is working to
develop a new silver corrosion test method. ASTM D4814
limits the silver corrosion rating to a maximum of “1.”
Hydrocarbon Composition
The three major types of hydrocarbons in gasoline are the sat-
urates (paraffins, isoparaffins, naphthenes), olefins, and aro-
matics. They are identified by ASTM D1319/IP 156, Test
Method for Hydrocarbon Types in Liquid Petroleum Products
by Fluorescent Indicator Adsorption. This method ignores oxy-
genates in the fuel and only measures the percentages of satu-
rates, olefins, and aromatics in the hydrocarbon portion of the
fuel. Therefore, the results must be corrected for any oxygen-

ates that are present. ASTM D6293, Test Method for Oxygen-
ates and Paraffin, Olefin, Naphthene, Aromatic (O-PONA)
Hydrocarbon Types in Low-Olefin Spark Ignition Engine Fuel
by Gas Chromatography, is another method. A more detailed
compositional analysis can be determined using one of the fol-
lowing methods: ASTM D6729, Test Method for Determina-
tion of Individual Components in Spark Ignition Engine Fuels
by 100 Metre Capillary High Resolution Gas Chromatography,
ASTM D6730, Test Method for Determination of Individual
Components in Spark Ignition Engine Fuels by 100 Metre
Capillary (with Precolumn) High Resolution Gas Chromatog-
raphy, or ASTM D6733, Test Method for Determination of
Individual Components in Spark Ignition Engine Fuels by
50 Metre Capillary High Resolution Gas Chromatography.
The amount of benzene can be determined by ASTM
D4053, Test Method for Benzene in Motor and Aviation Gaso-
line by Infrared Spectroscopy. The amounts of benzene and
other aromatics can be determined by ASTM D3606, Test
Method for Benzene and Toluene in Finished Motor and Avia-
tion Gasoline by Gas Chromatography, although there are inter-
ferences from methanol and ethanol. ASTM D5580, Test
Method for the Determination of Benzene, Toluene, Ethylben-
zene, p/m-Xylene, o-Xylene, C
9
and Heavier Aromatics, and
Total Aromatics in Finished Gasoline by Gas Chromatography,
and ASTM D5769, Test Method for Determination of Benzene,
Toluene, and Total Aromatics in Finished Gasoline by Gas Chro-
matography/Mass Spectrometry, can also be used. Another
method for the determination of aromatics is ASTM D5986,

Test Method for Determination of Oxygenates, Benzene, Tolu-
ene, C
8
-C
12
Aromatics and Total Aromatics in Finished Gasoline
by Gas Chromatography/Fourier Transform Infrared Spectros-
copy. The benzene content of reformulated gasoline is limited
to 1 volume percent by legislation, because benzene is consid-
ered toxic and a carcinogen. Beginning in 2011 under the
Mobile Source Air Toxics (MSAT) Rule, benzene will be con-
trolled for all gasoline at a refinery maximum average of 0.62
volume percent with a credit and trading program.
The total olefin content of automotive fuel can be deter-
mined by ASTM D6296, Test Method for Total Olefins in
Spark-Ignition Engine Fuels by Multi-dimensional Gas Chro-
matography, or by ASTM D6550, Test Method for Determina-
tion of Olefin Content of Gasolines by Supercritical-Fluid
Chromatography. The latter method has recently been desig-
nated by the California Air Resources Board as their stand-
ard test method for olefins.
Oxygenates
Oxygenates are discussed in detail later in this chapter, and
additional information on oxygenates is presented in Chapter 3.
Nevertheless, it is appropriate to mention here that alcohols
or ethers are often added to gasoline to improve octane rat-
ing, extend the fuel supply, or reduce vehicle emissions. Cer-
tain governmental regulations require such addition, as will
be discussed. Co nsequent ly, it is often necessary to deter-
mine the oxygenate content or the oxygen content of spark-

igniti on engine fuels. ASTM D4815, Test Method for Determi-
nation of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol
and C
1
to C
4
Alcohols in Gasoline by Gas Chromatograp hy,
can be used to determine the identity and conc entrations of
low-mo lecular-weight aliphatic alcohols and ethers . Alterna-
tive methods for determining the amounts of oxygenates are
ASTM D5599, Test Method for Determination of Oxygenates
in Gasoline by Gas Chromatography and Oxygen Selective
Flame Ionization Detection, and ASTM D5845, Test Method
for Determination of MTBE, ETBE, TAME, DIPE, Methanol,
Ethanol and tert-Butanol in Gasol ine by Infrared Spectros-
copy. Appendix X4 in Specification D4814 des cribes a proce-
dure for calculating the oxygen content of the fuel from the
oxygenate content.
Additives
Fuel additives are used to provide or enhance various per-
formance features related to the satisfactory operation of
engines, as well as to minimize fuel handling and storage
problems. These chemicals complement refinery processing
in attaining the desired level of product quality. The most
commonly used additives are listed in Table 1. With few
CHAPTER 2
n AUTOMOTIVE SPARK-IGNITION ENGINE FUEL 9

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exceptions, standardized test methods are not available to
determine the identity and concentration of specific additives.
As mentioned previously, standard test methods are available
for determining lead, manganese, and oxygenate content.
U.S. LEGAL REQUIREMENTS FOR
SPARK-IGNITION ENGINE FUEL
Fuel Composition
The U.S. EPA has established vehicle exhaust and evapora-
tive emissions standards as part of the U.S. effort to attain
acceptable ambient air quality. To meet these EPA vehicle
requirements, extensive modifications have been made to
automotive engines and emissions systems. Because some
fuel components can harm the effectiveness of vehicle emis-
sions control systems, the EPA also exercises control over
automotive fuels. EPA regulations on availability of unleaded
automotive fuels, and on limits of lead, phosphorus, and
manganese contents in the fuel, have been mentioned.
In addition, the Clean Air Act Amendments of 1977 pro-
hibit the introduction into U.S. commerce, or increases in
the concentration of, any fuel or fuel additive for use in
1975 and later light-duty motor vehicles, which is not
“substantially similar” to the fuel or fuel additives used in
the emissions certification of such vehicles.
The EPA considers fuels to be “substantially similar” if
the following criteria are met:
1. The fuel must contain carbon, hydrogen, and oxygen,
nitrogen, and/or sulfur, exclusively, in the form of some

combination of the following:
a. Hydrocarbons
b. Aliphatic ethers
c. Aliphatic alcohols other than methanol
(i) Up to 0.3 % methanol by volume
(ii) Up to 2.75 % methanol by volume with an
equal volume of butanol or higher-molecular-
weight alcohol
d. A fuel additive at a concentration of no more than
0.25 % by weight, which contributes no more than
15 ppm sulfur by weight to the fuel.
2. The fuel must contain no more than 2.0 % oxygen by
weight, except fuels containing aliphatic ethers and/or
alcohols (excluding methanol) and must contain no more
than 2.7 % oxygen by weight. (Note. As mentioned previ-
ously, ethanol and certain other alcohols have received
waivers allowing as much as 3.7 % oxygen in the fuel.)
3. The fuel must possess, at the time of manufacture, all of
the physical and chemical characteristics of an unleaded
gasoline, as specified by ASTM Standard D4814-88, for at
least one of the Seasonal and Geographical Volatility
Classes specified in the standard. (Note. The EPA’s Febru-
ary 11, 1991, notice specified the 1988 version of D4814.)
4. The fuel additive must contain only carbon, hydrogen,
and any one or all of the following elements: oxygen,
nitrogen, and/or sulfur.
Fuels or fuel additives that are not “substantially similar”
may only be used if a waiver of this prohibition is obtained
from the EPA. Manufacturers of fuels and fuel additives must
apply for such a waiver and must establish to the satisfaction

of the EPA that the fuel or additive does not cause or contrib-
ute to a failure of any emission control device or system over
the useful life of the vehicle for which it was certified. Under
prior law, if the EPA Administrator had not acted to grant or
TABLE 1—Commercial Spark-Ignition Engine Fuel Additives
Class Function Additive Type
Oxidation inhibitors (antioxidants) Minimize oxidation and gum formation Aromatic amines and hindered phenols
Corrosion inhibitors Inhibit ferrous corrosion in pipelines, stor-
age tanks, and vehicle fuel systems
Carboxylic acids and carboxylates
Silver corrosion inhibitors Inhibit corrosion of silver fuel gage sender
units
Substituted thiadiazole
Metal deactivators Inhibit oxidation and gum formation cata-
lyzed by ions of copper and other metals
Chelating agent
Carburetor/injector detergents Prevent and remove deposits in carburet-
ors and port fuel injectors
Amines, amides, and amine carboxylates
Deposit control additives Remove and prevent deposits throughout
fuel injectors, carburetors, intake ports and
valves, and intake manifold
Polybutene amines and polyether amines
Demulsifiers Minimize emulsion formation by improv-
ing water separation
Polyglycol derivatives
Anti-icing additives Minimize engine stalling and starting
problems by preventing ice formation in
the carburetor and fuel system
Surfactants, alcohols, and glycols

Antiknock compounds Improve octane quality of automotive fuel Lead alkyls and methylcyclopentadienyl
manganese tricarbonyl
Dyes, markers Identification of automotive fuel Oil-soluble solid and liquid dyes, organic
fluorescent compounds
Note. Some materials are multifunctional or multipurpose additives, performing more than one function. Source: SAE J312-Automotive Gasolines, Society
of Automotive Engineers, Inc.
10 SIGNIFICANCE OF TESTS FOR PETROLEUM PRODUCTS n 8TH EDITION

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deny the waiver within 180 days after its filing, the waiver
was treated as granted. The waiver process has been changed
to now require the EPA to act within 270 days. The EPA has
granted several waivers for gasoline-oxygenate blends. The
reader is referred to the EPA for the latest information on
waivers and the conditions under which they may be used.
Any fuel or fuel additive that had a waiver as of May 27,
1994, has to have had a supplemental registration with addi-
tional toxics data by November 27, 1994, to continue market-
ing the material. These registered products are subjected to
a three-tier toxicological testing program. A new fuel or addi-
tive that was not registered as of May 27, 1994, will not be
registered until all Tier 1 and Tier 2 information has been
supplied. At present, no methanol-containing fuel additive
has obtained a supplemental registration, and therefore, the
addition of methanol to gasoline is prohibited.
Volatility

Concerns over increased evaporative emissions prompted the
EPA to promulgate regulations that, beginning in 1989,
reduced fuel vapor pressure. Spark-ignition engine fuels sold
between June 1 and September 15 of each year were limited
to maximum vapor pressures of 9.0, 9.5, or 10.5 psi, depending
on the month and the region of the country. (Vapor pressure
restrictions applied to fuels in the distribution system as early
as May 1.) In 1992, the EPA implemented Phase II of the vola-
tility controls, which limited fuels sold between June 1 and
September 15 to a maximum vapor pressure of 9.0 psi. The
regulations are more restrictive in ozone nonattainment areas
in the southern and western areas of the United States, where
fuels sold during certain months of the control period are lim-
ited to a maximum vapor pressure of 7.8 psi. The EPA permits
conventional (i.e., not reformulated) fuels containing between
9 and 10 volume percent ethanol to have a vapor pressure 1.0
psi higher than the maximum limit for other fuels.
California was the first state to control spark-ignition
engine fuel vapor pressure and, in 1971, mandated a maxi-
mum vapor pressure limit of 9.0 psi. By 1992, the maximum
vapor pressure limit was lowered to 7.8 psi. In 1996, it was
further lowered to 7.0 psi maximum. A number of other
states have set maximum limits on vapor pressure in certain
areas as part of their SIPs. The EPA vapor pressure limits
and the EPA-approved SIP limits are an integral part of
ASTM D4814.
Sulfur Regulations
California’s Phase 2 reformulated gasoline specification lim-
ited the maximum sulfur content of fuel to 30 ppm average,
with an 80 ppm cap. On December 31, 2003, new Phase 3

specifications lowered the sulfur maximum to 15 ppm aver-
age and the cap limits to 60 ppm. The cap limits were fur-
ther reduced to 30 ppm on December 31, 2005.
Federal Tier 2 regulations required that in 2004, refiners
meet an annual corporate average sulfur level of 120 ppm,
with a cap of 300 ppm. In 2005, the required refinery average
was 30 ppm, with a corporate average of 90 ppm and a cap of
300 ppm. Both of the average standards can be met with the
use of credits generated by other refiners who reduce sulfur
levels early. Beginning in 2006, refiners were required to meet
a final 30 ppm average with a cap of 80 ppm. Fuel produced
for sale in parts of the western United States must comply
with a 150-ppm refinery average and a 300-ppm cap through
2006 but are required to meet the 30-ppm average/80-ppm
cap by 2007. Refiners demonstrating a severe economic hard-
ship may apply for an extension of up to two years. The regu-
lations provide for some special sulfur limit exemptions for
small refineries relating to the early introduction of ultralow
sulfur diesel fuel, but these all expire at the end of 2010. The
regulations include an averaging program. Some states
include fuel sulfur limits in their SIPs.
Sampling, Containers, and Sample Handling
Correct sampling procedures are critical to obtain a sample
representative of the lot intended to be tested. ASTM D4057,
Practice for Manual Sampling of Petroleum and Petroleum
Products, provides several procedures for manual sampling.
ASTM D4177, Practice for Automatic Sampling of Petroleum
and Petroleum Products, provides automatic sampling proce-
dures. For volatility determinations of a sample, ASTM
D5842, Practice for Sampling and Handling of Fuels for Vol-

atility Measurement, contains special precautions for sam-
pling and handling techniques to maintain sample integrity.
ASTM D4306, Practice for Aviation Fuel Sample Containers
for Tests Affected by Trace Contamination, should be used
to select appropriate containers, especially for tests sensitive
to trace contamination. Also ASTM D5854, Practice for Mix-
ing and Handling of Liquid Samples of Petroleum and Petro-
leum Products, provides procedures for container selection
and sample mixing and handling. For octane number deter-
mination, protection from light is important. Collect and
store fuel samples in an opaque container, such as a dark
brown glass bottle, metal can, or minimally reactive plastic
container, to minimize exposure to UV emissions from sour-
ces such as sunlight or fluorescent lamps.
Oxygenated Fuel Programs and Reformulated
Spark-Ignition Engine Fuel
In January 1987, Colorado became the first state to mandate
the use of oxygenated fuels in certain areas during the win-
ter months to reduce vehicle carbon monoxide (CO) emis-
sions. By 1991, areas in Arizona, Nevada, New Mexico, and
Texas had also implemented oxygenated-fuels programs.
The 1990 amendments to the Clean Air Act require the
use of oxygenated fuels in 39 CO nonattainment areas dur-
ing the winter months, effective November 1992. The pro-
gram had to be implemented by the states using one of the
following options. If averaging is allowed, the average fuel
oxygen content must be at least 2.7 mass percent, with a
minimum oxygen content of 2.0 mass percent in each gallon
of fuel. Without averaging, the minimum oxygen content of
each fuel must be 2.7 mass percent. (This is equivalent to

about 7.3 volume percent ethanol or 15 volume percent
MTBE.) The first control period was November 1, 1992,
through January or February 1993, depending on the area.
Subsequent control periods can be longer in some areas.
Over time a number of states have come into conformance
with CO regulations, and only about eight states still require
wintertime ethanol requirements.
Beginning in 1995, the nine areas with the worst ozone
levels, designated as extreme or severe, were required to sell
reformulated spark-ignition engine fuel. Later four additional
areas were added, but two are still pending implementation.
Areas with less severe ozone levels were permitted to partici-
pate in (“opt-in” to) the program. Initially, about 37 other
ozone nonattainment areas opted into participating in the
program. Since then, about 17 have chosen to opt-out of the
CHAPTER 2
n AUTOMOTIVE SPARK-IGNITION ENGINE FUEL 11

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program. The reformulated fuel program is directed toward
reducing ground level ozone and toxics concentrations.
The Clean Air Act Amendments of 1990 set specific
guidelines for reformulated spark-ignition engine fuel for
1995 through 1997. Fuels sold in the control areas were
required to meet the specifications of what is called the
“Simple Model.” Limits were established for vapor pressure

(June 1 through September 15) and benzene content,
deposit control additives were required in all fuels, and the
use of heavy-metal additives was prohibited. A minimum oxy-
gen content of 2.0 mass percent was required all year (aver-
aged). The sulfur and olefin contents and the 90 %
evaporated temperature were not allowed to exceed 125 %
of the average values of the refiner’s 1990 fuels. The use of
the “Simple Model” expired December 31, 1997.
Effective January 1, 1998, a “Complex Model” had to be
used for determining conformance to standards for reformu-
lated fuel blends. Fuel properties in the “Complex Model”
included vapor pressure, oxygen content, aromatics content,
benzene content, olefins content, sulfur content, E200 and
E300 (distillation properties), and the particular oxygenate
used. The benzene limit, the ban on heavy metals, the mini-
mum oxygen content, and the requirement for a deposit
control additive remained the same as under the “Simple
Model.” As a result of the adoption of the RFS, the mini-
mum oxygen requirement for reformulated fuel was elimi-
nated effective in 2006.
The Clean Air Act Amendments of 1990 also contain an
antidumping provision. In the production of reformulated
spark-ignition engine fuel, a refiner cannot “dump” into its
“conventional” fuel pool those polluting components
removed from the refiner’s reformulated fuel. These require-
ments apply to all fuel produced, imported, and consumed
in the United States and its territories.
In 1992, California instituted its Phase 1 fuel regula-
tions, which were followed in 1996 by its Phase 2 reformu-
lated fuel regulations. The Phase 2 specifications controlled

vapor pressure, sulfur content, benzene content, aromatics
content, olefins content, 50 % evaporated point, and 90 %
evaporated point. These same variables were used in Califor-
nia’s “Predictive Model,” which is similar to the federal
“Complex Model,” but with different equations. Beginning
December 31, 2003, California required fuel to meet a Phase
3 reformulated fuel regulation.
An excellent source of information on reformulated fuels
(federal and California) and their associated requirements can
be found in the ASTM Committee D02 on Petroleum Products
and Lubricants Research Report D02: 1347, Research Report
on Reformulated Spark-Ignition Engine Fuel for current fed-
eral and state future reformulated fuel (cleaner burning fuels)
requirements and approved test methods.
Renewable Fuel Standard
In 2007, the EPA finalized regulations for the RFS, which was
authorized by the Energy Policy Act of 2005. The RFS estab-
lishes a minimum requirement for the volume of renewable
fuels blended into automotive spark-ignition and diesel fuels.
The national minimum volume requirement started at 4.0 bil-
lion gallons per year of renewable fuel in 2006 and increases
to 7.5 billion gallons per year in 2012. Each producer and
importer of fuel in the United States is obligated to demon-
strate compliance with this requirement based on the pro
rata share of fuel it produces or imports. With the passage of
the Energy Independence and Security Act (EISA) of 2007,
the amount of renewable fuels required was increased to 15.2
billion gallons per year in 2012 and ends with a requirement
of 36.0 billion gallons per year by 2022. The proportional
requirement for cellulosic biofuel in the act begins in 2010

and scales up to 16.0 billion gallons per year by 2022.
Deposit Control Additive Requirements
California in 1992 and the EPA in 1995 required the use of
deposit control additives to minimize the formation of fuel
injector and intake valve deposits. Both California and the
EPA required that additives be certified in specified test fuels
in vehicle tests. The fuel injector test procedure is ASTM
D5598, Test Method for Evaluating Unleaded Automotive
Spark-Ignition Engine Fuel for Electronic Port Fuel Injector
Fouling, and the intake valve deposit test procedure is ASTM
D5500, Test Method for Vehicle Evaluation of Unleaded
Automotive Spark-Ignition Engine Fuel for Intake Valve
Deposit Formation. ASTM developed more recent, nonve-
hicle versions of these tests for consideration by the EPA.
These are ASTM D6201, Test Method for Dynamometer Eval-
uation of Unleaded Spark-Ignition Engine Fuel for Intake
Valve Deposit Formation, and ASTM D6421, Test Method for
Evaluating Automotive Spark-Ignition Engine Fuel for Elec-
tronic Port Fuel Injector Fouling by Bench Procedure.
GASOLINE-OXYGENATE BLENDS
Blends of gasoline with oxygenates are common in the U.S.
marketplace and, in fact, are required in certain areas, as dis-
cussed previously. These blends consist primarily of gasoline
with substantial amounts of oxygenates, which are oxygen-
containing, ashless, organic compounds such as alcohols and
ethers. The most common oxygenate in the United States is
ethanol. MTBE was widely used but has been phased out in
many states because of concern over ground water pollution.
It is still used in some European countries as an octane trim-
ming agent. Other ethers, such as ethyl tert-butyl ether

(ETBE), tert-amyl methyl ether (TAME), and diisopropyl ether
(DIPE), are receiving some attention, but have not yet
achieved widespread use. Like MTBE, these ethers also are
banned in some states. Methanol/tert-butyl alcohol mixtures
were blended with gasoline on a very limited scale in the
early 1980s but cannot be used now until they have a supple-
mental toxics registration. When methanol was used as a
blending component, it had to be accompanied by a cosol-
vent (a higher-molecular-weight alcohol) to help prevent
phase separation of the methanol and gasoline in the pres-
ence of trace amounts of water. EPA waiver provisions also
required corrosion inhibitors in gasoline-methanol blends.
ASTM D4806, Specification for Denatured Fuel Ethanol
for Blending with Gasolines for Use as Automotive Spark-
Ignition Engine Fuel, describes a fuel-grade ethanol that is
suitable for blending with gasoline. ASTM D5983, Specifica-
tion for Methyl Tertiary-Butyl Ether (MTBE) for Downstream
Blending with Automotive Spark-Ignition Fuel, provides lim-
its for blending MTBE in gasoline.
Sampling of Gasoline-Ox ygenate Blends
Sampling of blends can be conducted according to the pro-
cedures discussed earlier; however, water displacement must
not be used, because of potential problems associated with
the interaction of water with oxygenates contained in some
spark-ignition engine fuels.
12 SIGNIFICANCE OF TESTS FOR PETROLEUM PRODUCTS
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Test Methods for Gasoline-Oxygenate Blends
Some of the test methods originally developed for gasoline
can be used for gasoline-oxygena te blends, while certain
other test methods for gasoline are not suitable for blends.
To avoid the necessity of determining in advance whether a
fuel contains oxygenates, ASTM D4814 now specifies test
methods that can be used for both gasolines and gasoline-
oxygenate blends. This has been made possible by experi-
ence with some test methods, modification of existing test
methods, and the development of new ones. Gasoline-
ethanol blends are not included in the scopes of many test
methods, and the precision statements do not apply. ASTM
is working to modify the scopes and develop precision
statements for the test methods specified in ASTM D4814
to cover gasoline-ethanol blends. Additional test methods
and limits need to be developed to protect against incom-
patibility with elastomers and plastics, corrosion of metals,
and other factors that may affect vehicle performance and
durability.
In general, the test methods discussed previously for
determining distillation temperatures, lead content, sulfur
content, copper corrosion, solvent-washed gum, and oxida-
tion stability can be used for both gasolines and gasoline-oxy-
genate blends. In some cases, standard solutions with which
to calibrate the instrument must be prepared in the same
type of fuel blend as the sample to be analyzed.
Some of the test methods for vapor pressure and vapor/

liquid ratio are sensitive to the presence of oxygenates in the
fuel, and approved procedures were discussed earlier in this
chapter.
Water Tolerance
The term “water tolerance” is used to indicate the ability of a
gasoline-alcohol blend to dissolve water without phase separa-
tion. Gasoline and water are almost entirely immiscible and
will readily separate into two phases. Gasoline-alcohol blends
will dissolve some water but will also separate into two phases
when contacted with more water than they can dissolve. This
water can be absorbed from ambient air or can occur as liq-
uid water in the bottom of tanks in the storage, distribution,
and vehicle fuel system. When gasoline-alcohol blends are
exposed to a greater amount of water than they can dissolve,
about 0.1 to 0.7 mass percent water, they separate into a
lower alcohol-rich aqueous phase and an upper alcohol-poor
hydrocarbon phase. The aqueous phase can be corrosive to
metals, and the engine cannot operate on it. Because the fuel
pump is at the bottom of an automotive fuel tank, the aque-
ous phase will be sent to the engine if the fuel separates.
Therefore, this type of phase separation is undesirable. Sepa-
ration occurs more readily with the lower-molecular-weight
alcohols and at lower alcohol concentrations. With ethanol,
the 10 volume percent levels used in the United States are eas-
ily handled; however, the 5 volume percent levels used in
Europe are much more sensitive to separation. Several years
of experience in California with 5.7 volume percent ethanol
has shown no phase separation problems using ethanol meet-
ing a 1.0 volume percent maximum water content limit.
Phase separation can usually be avoided if the fuels are

sufficiently water free initially and care is taken during dis-
tribution to prevent contact with water. Formation of a haze
must be carefully distinguished from separation into two dis-
tinct phases with a more or less distinct boundary. Haze for-
mation is not grounds for rejection. Actual separation into
two distinct phases is the criterion for failure. The test
method originally developed to measure the water tolerance
of ethanol blends was determined in an interlaboratory
study to not be sufficiently accurate and was withdrawn. The
limits were removed from the specification section of ASTM
D4814 and placed in Appendix X8 for reference. The need
for a water tolerance test is still thought to be important,
and a water tolerance specification would be included in
ASTM D4814 if a suitable test can be developed.
Compatibility with Plastics and Elastomers
Plastics and elastomers used in current automotive fuel sys-
tems such as gaskets, O-rings, diaphragms, filters, seals, etc.,
may be affected in time by exposure to motor fuels. These
effects include dimensional changes, embrittlement, soften-
ing, delamination, increase in permeability, loss of plasticiz-
ers, and disintegration. Certain gasoline-oxygenate blends
can aggravate these effects.
The effects depend on the type and amount of the oxy-
genates in the blend, the aromatics content of the gasoline,
the generic polymer and specific composition of the elasto-
meric compound, the temperature and duration of contact,
and whether the exposure is to liquid or vapor.
Currently, there are no generally accepted tests that cor-
relate with field experience to allow estimates of tolerance
of specific plastics or elastomers to oxygenates.

Metal Corrosion
Corrosion of metals on prolonged contact with gasolines alone
can be a problem, but it is generally more severe with gasoline-
alcohol blends. When gasoline-alcohol blends are contacted by
water, the aqueous phase that separates is particularly aggres-
sive in its attack on fuel system metals. The tern (lead-tin alloy)
coating on fuel tanks and aluminum, magnesium, and zinc
castings and steel components such as fuel senders, fuel lines,
pump housings, and injectors are susceptible.
A number of test procedures, other than long-term vehi-
cle tests, have been used or proposed to evaluate the corro-
sive effects of fuels on metals. The tests range from static
soaking of metal coupons to operation of a complete auto-
motive fuel system. None of these tests has yet achieved the
status of an ASTM standard.
Applicable ASTM Specifications
ASTM Title
D4806 Specification for Denatured Fuel Ethanol for
Blending with Gasolines for Use as Automotive
Spark-Ignition Engine Fuel
D4814 Specification for Automotive Spark-Ignition Engine
Fuel
D5797 Specification for Fuel Methanol (M70-M85) for
Automotive Spark-Ignition Engines
D5798 Specification for Fuel Ethanol (Ed75-Ed85) for
Automotive Spark-Ignition Engines
D5983 Specification for Methyl Tertiary-Butyl Ether
(MTBE) for Downstream Blending with Auto-
motive Spark-Ignition Engine Fuel
D02:1347 Committee D02 Research Report on Reformulated

Spark-Ignition Engine Fuel
CHAPTER 2 n AUTOMOTIVE SPARK-IGNITION ENGINE FUEL 13

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Applicable ASTM/IP Test Methods
Before using any test method, the scope shall be reviewed to make
sure the test method is applicable to the product being tested and
that the specified measurement range covers the area of interest.
ASTM IP Title
D86 Test Method for Distillation of Petroleum
Products at Atmospheric Pressure
D130 154 Test Method for Detection of Copper
Corrosion from Petroleum Products by the
Copper Strip Tarnish Test
D323 Test Method for Vapor Pressure of Petro-
leum Products (Reid Method)
D381 Test Method for Gum Content in Fuels by
Jet Evaporation
D525 40 Test Method for Oxidation Stability of
Gasoline (Induction Period Method)
D665 135 Test Method for Rust-Preventing Character-
istics of Inhibited Mineral Oil in the Pres-
ence of Water
D873 138 Test Method for Oxidation Stability of Avia-
tion Fuels (Potential Residue Method)
D1266 107 Test Method for Sulfur in Petroleum Prod-

ucts (Lamp Method)
D1298 160 Test Method for Density, Relative Density
(Specific Gravity), or API Gravity of Crude
Petroleum and Liquid Petroleum Products
by Hydrometer Method
D1319 156 Test Method for Hydrocarbon Types in Liq-
uid Petroleum Products by Fluorescent Indi-
cator Adsorption
D2276 216 Test Method for Particulate Contaminant in
Aviation Fuel by Line Sampling
D2622 Test Method for Sulfur in Petroleum Prod-
ucts by Wavelength Dispersive X-Ray Fluo-
rescence Spectrometry
D2699 237 Test Method for Research Octane Number
of Spark-Ignition Engine Fuel
D2700 236 Test Method for Motor Octane Number of
Spark-Ignition Engine Fuel
D2709 Test Method for Water and Sediment in
Distillate Fuels by Centrifuge
D2885 360 Test Method for Research and Motor Method
Octane Ratings Using On-Line Analyzers
D3120 Test Method for Trace Quantities of Sulfur
in Light Liquid Petroleum Hydrocarbons by
Oxidative Microcoulometry
D3227 342 Test Method for (Thiol Mercaptan) Sulfur in
Gasoline, Kerosene, Aviation Turbine, and
Distillate Fuels (Potentiometric Method)
D3231 Test Method for Phosphorus in Gasoline
D3237 Test Method for Lead in Gasoline by Atomic
Absorption Spectroscopy

ASTM IP Title
D3341 Test Method for Lead in Gasoline–Iodine
Monochloride Method
D3348 Test Method for Rapid Field Test for Trace
Lead in Unleaded Gasoline (Colorimetric
Method)
D3606 Test Method for Determination of Benzene
and Toluene in Finished Motor and Aviation
Gasoline by Gas Chromatography
D3703 Test Method for Peroxide Number of
Aviation Turbine Fuels
D3710 Test Method for Boiling Range Distribution
of Gasoline and Gasoline Fractions by Gas
Chromatography
D3831 Test Method for Manganese in Gasoline by
Atomic Absorption Spectroscopy
D4045 Test Method for Sulfur in Petroleum Products
by Hydrogenolysis and Rateometric Co lorimetry
D4052 365 Test Method for Density and Relative Den-
sity of Liquids by Digital Density Meter
D4053 Test Method for Benzene in Motor and
Aviation Gasoline by Infrared Spectroscopy
D4057 Practice for Manual Sampling of Petroleum
and Petroleum Products
D4177 Practice for Automatic Sampling of
Petroleum and Petroleum Products
D4294 Test Method for Sulfur in Petroleum and
Petroleum Products by Energy-Dispersive
X-Ray Fluorescence Spectrometry
D4306 Practice for Aviation Fuel Sample Containers

for Tests Affected by Trace Contamination
D4815 Test Method for Determination of MTBE,
ETBE, TAME, DIPE, tertiary-Amyl Alcohol
and C
1
to C
4
Alcohols in Gasoline by Gas
Chromatography
D4952 Test Method for Qualitative Analysis for
Active Sulfur Species in Fuels and Solvents
(Doctor Test)
D4953 Test Method for Vapor Pressure of Gasoline
and Gasoline-Oxygenate Blends (Dry
Method)
D5059 228 Test Methods for Lead in Gasoline by X-Ray
Spectroscopy
D5188 Test Method for Vapor-Liquid Ratio Tem-
perature Determination of Fuels (Evacuated
Chamber Method)
D5190 Test Method for Vapor Pressure of Petro-
leum Products (Automatic Method)
D5191 Test Method for Vapor Pressure of Petro-
leum Products (Mini Method)
D5453 Test Method for Determination of Total
Sulfur in Light Hydrocarbons, Spark Ignition
Engine Fuel and Engine Oil by Ultraviolet
Fluorescence
14 SIGNIFICANCE OF TESTS FOR PETROLEUM PRODUCTS n 8TH EDITION

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ASTM IP Title
D5482 Test Method for Vapor Pressure of
Petroleum Products (Mini Method-
Atmospheric)
D5500 Test Method for Vehicle Evaluation of
Unleaded Automotive Spark-Ignition Engine
Fuel for Intake Valve Deposit Formation
D5580 Test Method for Determination of Benzene,
Toluene, Ethylbenzene, p/m-Xylene,
o-Xylene, C
9
and Heavier Aromatics, and
Total Aromatics in Finished Gasoline by Gas
Chromatography
D5598 Test Method for Evaluating Unleaded Auto-
motive Spark-Ignition Engine Fuel for Elec-
tronic Port Fuel Injector Fouling
D5599 Test Method for Determination of Oxygen-
ates in Gasoline by Gas Chromatography
and Oxygen Selective Flame Ionization
Detection
D5769 Test Method for Determination of Benzene,
Toluene, and Total Aromatics in Finished
Gasoline by Gas Chromatography/Mass
Spectrometry

D5842 Practice for Sampling and Handling of Fuels
for Volatility Measurement
D5845 Test Method for Determination of MTBE,
ETBE, TAME, DIPE, Methanol, Ethanol and
tert-Butanol in Gasoline by Infrared
Spectroscopy
D5854 Practice for Mixing and Handling of Liquid
Samples of Pe troleum and Petroleum Products
D5986 Test Method for Determination of Oxygen-
ates, Benzene, Toluene, C
8
-C
12
Aromatics
and Total Aromatics in Finished Gasoline by
Gas Chromatography/Fourier Transform
Infrared Spectroscopy
D6201 Test Method for Dynamometer Evaluation
of Unleaded Spark-Ignition Engine Fuel for
Intake Valve Deposit Formation
D6293 Test Method for Oxygenates and Paraffin,
Olefin, Naphthene, Aromatic (O-PONA)
Hydrocarbon Types in Low-Olefin Spark
Ignition Engine Fuel by Gas
Chromatography
D6296 Test Method for Total Olefins in Spark-
Ignition Engine Fuels by Multi-dimensional
Gas Chromatography
D6334 Test Method for Sulfur in Gasoline by
Wavelength Dispersive X-Ray Fluorescence

ASTM IP Title
D6378 Test Method for Determination of Vapor
Pressure (VP
X
) of Petroleum Products,
Hydrocarbons, and Hydrocarbon-Oxygenate
Mixtures (Triple Expansion Method)
D6421 Test Method for Evaluating Automotive
Spark-Ignition Engine Fuel for Electronic
Port Fuel Injector Fouling by Bench
Procedure
D6445 Test Method for Sulfur in Gasoline by
Energy-Dispersive X-Ray Fluorescence
Spectrometry
D6447 Test Method for Hydroperoxide Number of
Aviation Turbine Fuels by Voltammetric
Analysis
D6469 Guide for Microbial Contamination in Fuels
and Fuel Systems
D6550 Test Method for Determination of Olefin
Content of Gasolines by Supercritical-Fluid
Chromatography
D6729 Test Method for Determination of Individ-
ual Components in Spark Ignition Engine
Fuels by 100 Metre Capillary High Resolu-
tion Gas Chromatography
D6730 Test Method for Determination of Individ-
ual Components in Spark Ignition Engine
Fuels by 100 Metre Capillary (with Precol-
umn) High Resolution Gas Chromatography

D6733 Test Method for Determination of Individ-
ual Components in Spark Ignition Engine
Fuels by 50 Metre Capillary High Resolution
Gas Chromatography
D6920 Test Method for Total Sulfur in Naphthas,
Distillates, Reformulated Gasolines, Diesels,
Biodiesels, and Motor Fuel by Oxidative
Combustion and Electrochemical
Detection
D7039 Test Method for Sulfur in Gasoline and Die-
sel Fuel by Monochromatic Wavelength Dis-
persive X-Ray Fluorescence Spectrometry
D7096 Test Method for Determination of the Boil-
ing Range Distribution of Gasoline by Wide-
Bore Capillary Gas Chromatography
D7344 Test Method for Distillation of Petroleum
Products at Atmospheric Pressure (Mini
Method)
D7345 Test Method for Distillation of Petroleum
Products at Atmospheric Pressure (Micro
Distillation Method)
CHAPTER 2 n AUTOMOTIVE SPARK-IGNITION ENGINE FUEL 15

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3
Fuel Oxygenates

Marilyn J. Herman
1
and Lewis M. Gibbs
2
FUEL OXYGENATES ARE WIDELY USED IN THE
United States. In the late 1970s and early 1980s, as lead anti-
knocks were removed from motor gasoline, gasoline pro-
ducers used oxygenates to offset the loss in octane number
from the removal of lead. In the 1990s, oxygenates were
required by the government as an emission reduction control
strategy. More recently, the United States has required the use
of renewable fuels in order to help reduce U.S. dependence
on foreign sources of oil. In December 2007, the President
signed into law the Energy Independence and Security Act of
2007 (P.L. 110-140). The Energy Independence and Security
Act of 2007 (EISA) significantly expands and increases the
Renewable Fuels Standard established under the Energy Pol-
icy Act of 2005 requiring the use of 9.0 billion gallons of
renewable fuel in 2008, increasing to 36 billion gallons by
2022. In 2022, 21 billion gallons of the total renewable fuels
requirement must be obtained from cellulosic ethanol and
other advanced biofuels.
Under the Clean Air Act, oxygenates have been used as
an emission control strategy to reduce carbon monoxide
(CO) in wintertime oxygenated fuel programs and as a
required component in federal reformulated gasoline pro-
grams to help reduce ozone. The Clean Air Act Amendments
(CAA) of 1990 require states with areas exceeding the
national ambient air quality standard for carbon monoxide
to implement programs requiring the sale of oxygenated gas-

oline containing a minimum of 2.7 weight percent oxygen
during the winter months.
The Clean Air Act Amendments also require the use of
reformulated gasoline (RFG) in those areas of the United
States with the most severe ozone pollution. Under the Clean
Air Act Amendments and the Energy Policy Act of 1992, Con-
gress enacted legislation requiring the use of alternative fuels
and alternative fuel vehicles. Fuels containing high concen-
trations of ethanol or methanol, where oxygenate is the pri-
mary component of the blend, qualify as alternative fuels.
E85, a blend of 85 volume percent ethanol and 15 volume
percent hydrocarbons, and M85, a blend of 85 volume per-
cent methanol and 15 volume percent hydrocarbons, may be
used in specially designed vehicles to comply with state and
local alternative fuel programs.
An oxygenate is defined under ASTM specifications as
an oxygen-containing, ashless, organic compound, such as
an alcohol or ether, which can be used as a fuel or fuel sup-
plement. A gasoline-oxygenate blend is defined as a fuel con-
sisting primarily of gasoline along with a substantial amount
(more than 0.35 mass percent oxygen, or more than 0.15
mass percent oxygen if methanol is the only oxygenate) of
one or more oxygenates.
While there are several oxygenates that can be used to
meet federal oxygen requirements in gasoline, ethanol is cur-
rently the primary oxygenate used to comply with Clean Air
Act requirements. While methyl tertiary-butyl ether (MTBE)
had been used to meet Clean Air Act requirements, state
legislation banning the use of MTBE in gasoline has virtually
eliminated its use in the United States. Other oxygenates,

such as methanol, tertiary-amyl methyl ether (TAME), ethyl
tertiary-butyl ether (ETBE), and diisopropyl ether (DIPE)
have been used in much sma ller quantities. In the early
1980s, methanol/tertiary-butyl alcohol mixtures were blended
with gaso line on a limited scale. When methanol is used as
a blending component, it must be accompanied by a co-sol-
vent (a higher molecular weight alcohol) to help prevent
phase separation of the methanol and gasoline in the pres-
ence of trace amounts of water.
Oxygenated fuels are subject to a number of federal reg-
ulations. The U.S. Environmental Protection Agency regu-
lates the allowable use of oxygenates in unleaded gasoline
and is responsible for promulgating regulations and enforc-
ing the Renewable Fuels Standard program. The Alcohol and
Tobacco Tax and Trade Bureau (TTB) of the Department of
Treasury regulates the composition of alcohol used for fuel.
The Internal Revenue Service (IRS) regulates the characteris-
tics of fuels qualifying for special tax treatment.
This chapter focuses on ethanol and other oxygenates
for use as blending components in fuel or for use as high
ethanol content fuels in spark-ignition engines. This chapter
summarizes the significance of the more important physical
and chemical characteristics of these oxygenates and the per-
tinent test methods for determining these properties. Infor-
mation on government regulations and tax incentives for
oxygenated fuels is provided. ASTM specifications for oxy-
genates and other biofuels discussed are:
• ASTM D4806, Specification for Denatured Fuel Ethanol
for Blending with Gasolines for Use as Automotive Spark-
Ignition Engine Fuel, covers a denatured fuel ethanol suit-

able for blending up to 10 volume percent with gasoline.
• ASTM D5798, Specification for Fuel Ethanol (Ed75-
Ed85) for Automotive Spark-Ignition Engines, covers a
fuel blend, nominally 75 to 85 volume percent denatured
fuel ethanol and 25 to 15 additional volume percent
hydrocarbons for use in ground vehicles with automotive
spark-ignition engines.
• ASTM D5797, Specification for Fuel Methanol M70-M85
for Automotive Spark-Ignition Engine Fuels, covers a
fuel blend, nominally 70 to 85 volume percent methanol
and 30 to 15 volume percent hydrocarbons for use in
ground vehicles with automotive spark-ignition engines.
1
Herman and Associates, Washington, DC.
2
Chevron Products Company, Richmond, CA.
16
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MNL1-EB/May 2010
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