Proper Fuel for Cummins Engines
This bulletin covers information about Fuels for Cummins® Engines. The purpose of this
bulletin is to help the user understand proper fuel selection and problems associated with fuel.
Diesel Fuel
Diesel fuel performs three major functions in a Cummins® diesel engine.
It supplies all the energy for the engine.
It cools and lubricates the precision parts of the engine's fuel pump and injectors.
It enables emissions controlled engines to meet regulated emissions levels.
Cummins® diesel engines will run on a great variety of fuels, but some fuels will give better
performance, higher efficiency, improved reliability, or lower maintenance costs than others.
CAUTION
Engines equipped with exhaust aftertreatment must operate on ultra-low sulfur diesel (ULSD),
with a maximum sulfur content of 15 ppm in the US and Canada, and 10 ppm in Europe.
Failure to do so will result in damage to the aftertreatment system.
Required Diesel Fuel Specifications
This section presents the Cummins Inc. required fuel specifications.
Fuels meeting national and international specifications can be used if they observe the
specifications listed in Table 1: Required Diesel Fuel Specifications. Cummins® engines will
operate satisfactorily on fuels meeting all the properties listed in Table 1; however, fuels
meeting only the required specifications will not give the same level of performance, efficiency,
reliability, or maintenance costs as premium fuels.
Table 1: Required Diesel Fuel Specifications
Viscosity 1.3 to 4.1 centistokes at 40°C [104°F]
Cetane Number 42 minimum above 0°C [32°F]; 45 minimum below 0°C [32°F]
Sulfur Content Not to exceed 5000 ppm. Other regional regulations may apply.
In the US and Canada, 2007 and later on-highway engines require the use of ULSD (15 ppm
maximum). 1 Active Sulfur Copper Strip Corrosion not to exceed Number 3 rating after 3 hours at 50°C
[122°F]
Water Sediment Not to exceed 0.05 volume-percent
Carbon Residue Not to exceed 0.35 mass-percent on 10 volume-percent residuum
Density 0.816 to 0.876 grams per cubic centimeter (g/cc) at 15°C [59°F]
Cloud Point 6°C [10°F] below lowest ambient temperature at which the fuel is expected to
operate
Ash Not to exceed 0.02 mass-percent 2
Distillation The distillation curve must be smooth and continuous
Lubricity HFRR 0.52 mm maximum: Wear Scar Diameter (WSD) at 60°C [140°F] HFRR
Regional, national, or international regulations can require a lower sulfur content than 5000
ppm. Consult all applicable regulations before selecting a fuel for a given engine application.
Fuel with sulfur higher than 5000 ppm is not allowed without Cummins Inc. prior approval.
Fuel system corrosion, heightened emissions, and reduced oil drain intervals are just some of
the possible adverse effects of fuels with very high sulfur. Fuel must meet proper flash point
requirements to satisfy local safety regulations.
For vehicles equipped with exhaust aftertreatment, there shall be no detectable ash in the fuel.
Diesel Fuel Properties
Viscosity
General Description - Proper viscosity provides adequate pumping and lubricating
characteristics to fuel system components.
Test Method - ASTM D445, ISO 3104
Cetane Number
General Description - Cetane number is a measure of the starting and warm-up characteristics
of a fuel. In cold weather or in service with prolonged low loads, a higher cetane number is
desirable.
Test Method - ASTM D613, ISO 5165
Fuel with a cetane number greater than 55 can cause increased torque peak smoke.
Reference ASTM D613, ISO 5165.
Sulfur Content
General Description - Diesel fuels contain varying amounts of various sulfur compounds. Fuel
sulfur contributes to acid formation and exhaust particulates. Reduced sulfur is required to
meet particulate emissions and to avoid poisoning aftertreatment devices. Higher sulfur fuel
also needs higher total base number (TBN) lubricants to compensate for acid corrosion.
Test Method - ASTM D2622, ISO 4260
NOTE: Catalyst failures caused by the use of fuels with higher than recommended sulfur
levels are not warrantable. High sulfur fuel will also shorten the life of certain components in
the exhaust system, including the oxidation catalyst.
Active Sulfur
General Description - Some sulfur compounds in fuel are actively corrosive.
Test Method - ASTM D130, ISO 2160
Water and Sediment
General Description - The amount of water and solid debris in the fuel is generally classified
as water and sediment. It is good practice to filter fuel while it is being put into the fuel tank.
More water vapor condenses in partially filled tanks due to tank breathing caused by
temperature changes. Filter elements, fuel screens in the fuel pump, and fuel inlet connections
on injectors must be cleaned or replaced whenever they become dirty. These screens and
filters, in performing their intended function, become clogged when using a poor or dirty fuel
and will need to be changed more often. Test Method - ASTM DI796
Carbon Residue
General Description - The tendency of a diesel fuel to form carbon deposits in an engine can
be estimated by determining the Ramsbottom or Conradson carbon residue of the fuel after 90
percent of the fuel has been evaporated.
Test Method - ASTM D524, ASTM D189, ISO 10370
Density
General Description - Density is an indication of the energy content of the fuel. Higher density
indicates more thermal energy and better fuel economy.
Test Method - ASTM D287, D4052, ISO 3675
Cloud Point
General Description - The cloud point of the fuel is the temperature at which crystals of
paraffin wax first appear. Crystals can be detected by the cloudiness of the fuel.
Test Method - ASTM D97, ISO 3015
Cold Filter Plugging Point
General Description - The cold filter plugging point of the fuel is the lowest temperature at
which fuel can still flow through a 45 micron wire mesh. This test method can be directly
related to a fuel's tendency to plug fuel filters at reduced temperatures, due to the formation of
paraffin wax crystals.
Test Method - ASTM D6371
Ash
General Description - The small amount of noncombustible metallic material commonly found
in almost all petroleum products is called ash.
Test Method - ASTM D482, ISO 6245
Distillation
General Description - At least 90 percent of the fuel must evaporate at less than 360°C
[680°F]. All of the fuel must evaporate at less than 385°C [725°F].
Test Method - ASTM D86, ISO 3405
Lubricity (ball on cylinder evaluator) BOCLE
General Description - Lubricity is the ability of a liquid to provide hydrodynamic and boundary
lubrication to prevent wear between moving parts. Fuel with lower sulfur and viscosity tends to
have lower lubricity. It can be measured by either one of two procedures.
Test Method: ASTM D6078, Scuffing Load Ball On Cylinder Evaluator (SLBOCLE), or ASTM
D6079, ISO 12156, High Frequency Reciprocating Rig (HFRR)
Ultra-Low Sulfur Diesel
Ultra-low sulfur diesel (ULSD) fuel is defined as diesel fuel not exceeding 0.0015 mass
percent (15 ppm) sulfur content. The following Cummins® engines are required to operate on
ULSD.
2007 and later on-highway engines in the United States and Canada equipped with exhaust
aftertreatment devices.
Engines operating where regional, national, or international regulations require the use of
ULSD in diesel engines.
The use of ULSD is essential for lowering exhaust emissions, protecting the environment, and
for proper functionality of modern exhaust aftertreatment devices. The low sulfur content does
slightly change some of the fuel properties. However, transitioning from low sulfur diesel
(LSD), which can contain up to 500 ppm sulfur, to ULSD can go smoothly if, a few precautions
are taken, such as: Properly label all fuel tanks and delivery pumps.
Be sure the fuel lubricity meets the Cummins® Required Diesel Fuel Specifications outlined in
Table 1 of this bulletin.
ULSD has lower lubricity than LSD, so lubricity additives need to be added by the fuel supplier
to prevent fuel system damage. More information on fuel additives can be found in the
“Additives” section of this service bulletin.
Be sure that fuel tanks are completely empty before transitioning from LSD to ULSD, and
consider tank cleaning.
It takes only a small amount of LSD blended with ULSD to bring the fuel sulfur content above
15 ppm.
Consider using a stability additive for fuel in bulk storage.
ULSD is more prone to oxidation than LSD. Consult your fuel supplier to determine if an
additive is needed to maintain fuel quality in storage tanks.
Closely monitor fuel system for leaks, especially when first transitioning to ULSD, and correct
them immediately.
ULSD reacts differently than LSD with certain seal and gasket compounds commonly found in
fuel systems, which means that leaks are more likely to occur, especially in older engines
which were designed to run on LSD.
Contingency Diesel Fuel Specifications
This section presents the specifications for fuels which are only to be used when fuel meeting
the required specifications is not available. In the case that fuels meeting the Required
Specifications in Table 1 are not available, Cummins Inc. has prepared contingency
specifications to aid the user in choosing the most acceptable contingency fuel.
CAUTION
Fuels outside the recommended fuel specifications, but within the contingency specifications,
are only meant to be used for short periods of time when no other fuels are available. Use of
contingency fuels can have an adverse effect on engine performance and durability.
Cummins® assumes no warranty responsibility for repairs or increased costs of operation
resulting from the use of fuels that do not conform to the specifications listed in Table 1.
Guidelines for the Use of Contingency Fuels
A calibration change of the fuel pump or injectors is not recommended when changing to a
contingency fuel that meets all the specifications shown in the Contingency Diesel Fuel
Specifications, although changing to a contingency fuel can cause a slight power loss and can
result in higher than normal wear of certain components. See the sections in this bulletin on
Power Loss and Component Wear and Durability for additional information.
Although it is not anticipated that smoke levels will increase when fuels meeting the
contingency fuel specifications are used for short periods of time, the user must make sure
that the use of such fuels does not result in a smoke level which exceeds legal limits applied
to the owner or operator. Continued use of fuels meeting the contingency fuel specifications
can result in increased smoke levels.
Some jet fuel lubricities can be too low to provide the necessary lubrication for the fuel system
components. If (based on the fuel supplier's specifications) a fuel does not have the minimum
lubricity listed for contingency fuels in Contingency Diesel Fuel Specifications, a fuel additive
must be added to the fuel to increase the lubricity and specially enhanced fuel system components must be used. Go to the section in this bulletin on fuel additives. Consult
Cummins Inc. for available hardware options.
\WARNING
Some contingency fuels, such as jet fuels and kerosene, are much more flammable than
normal diesel fuel. Use extreme care to keep cigarettes, flames, pilot lights, sparks, arcing
equipment and switches, and other sources of ignition away and out of areas sharing
ventilation.
Additional maintenance can be required when using contingency fuels. Those using
contingency fuels must consult with their fuel supplier to determine any problems which can
result from using fuels meeting Contingency Diesel Fuel Specifications. If there is still a
question, data on the fuel's physical properties must be submitted to the Cummins® Service
Engineering Department for review before use in Cummins® engines.
Table 2: Contingency Diesel Fuel Specifications 1
Viscosity 1.3 to 13.1 centistokes at 40°C [104°F]
Cetane Number 35 minimum above 0°C [32°F]; 40 minimum below 0°C [32°F]
Sulfur Content Less than 2.0 mass-percent (20,000 ppm). Catalyst equipped engines will not
be able to use high sulfur fuel, even for a short period of time, without permanent damage to
the catalyst.
Active Sulfur Copper Strip Corrosion not to exceed Number 2 rating after 3 hours at 50°C
[122°F]
Water and Sediment Not to exceed 0.5 volume-percent
Carbon Residue Not to exceed 5.0 mass-percent on 10 volume-percent residuum
Density 0.750 to 0.965 g/cc at 15°C
Cloud Point 6°C [10°F] below lowest ambient temperature at which the fuel is expected to
operate
Ash Not to exceed 0.05 mass-percent
Distillation 90 volume-percent at 395°C [743°F]
Lubricity (ball on cylinder evaluator) SLBOCLE Minimum of 2300 grams SLBOCLE, maximum
of 0.6 mm Wear Scar Diameter WSD at 60°C [140°F] HFRR
Vanadium 5 ppm, maximum
Aluminum 1 ppm, maximum
Silicon 1 ppm, maximum
Sodium 10 ppm, maximum
Reference test methods in Diesel Fuel Properties
Effects of Contingency Diesel Fuels on Engine Operation
Viscosity
Low viscosity causes rapid wear of fuel pump and injectors. High viscosity causes hard
starting, white smoke when cold, injector cup cracking, and injector train failures. Governor
wear on rotary fuel pumps can cause loss of regulation.
Cetane Number
A cetane number below 42 can cause poor starting, excessive white smoke, and poor idling. A
cetane number above 55 can increase smoke at peak torque conditions.
Sulfur Content High sulfur content increases wear in injectors, piston rings, and bearings. Use of fuels with
sulfur content above 5000 ppm requires the use of higher total base number (TBN) lubricants
(TBN greater than 10) and shorter oil drain intervals.
CAUTION
Catalyst failures caused by the use of fuels with higher than recommended sulfur levels are
not warrantable. High sulfur fuel will also shorten the life of certain components in the exhaust
system, including the oxidation catalyst.
Active Sulfur
Excessive active sulfur increases the corrosive attack on the fuel pump, injectors, and other
fuel system components.
Water and Sediment
Contaminated fuels reduce filter life, fuel system life, and cause on-road failures.
Carbon Residue
High carbon residue causes increased combustion chamber carbon deposits, more exhaust
smoke, and higher soot contamination of the lubricating oil.
Density
Lighter fuels contain less thermal energy per gallon and result in somewhat lower fuel
economy. A fuel with a density of 0.876 g/cc contains about 3.5 percent more energy per
gallon than a fuel with a density of 0.815 g/cc.
Cloud Point
Operating below the cloud point temperature can cause the fuel filter to clog with wax crystals,
restrict fuel flow, and cause loss of power. It is suggested that if fuels with cloud points above
the expected ambient temperatures are purchased, the consumer must consult the fuel
supplier and Cummins Inc. concerning fuel handling techniques. For more information, go to
Common Issues With Winter Fuel.
Pour Point
Operating near or below the pour point will cause start-up issues. It is doubtful that most fuel
pumps can operate at the pour point. In fact, it is recommended that systems be operated at
5.5°C to 8°C [10°F to 15°F] above the pour point of a fuel.
Cold Filter Plugging Point
Operating below the cold filter plugging point temperature will cause the fuel filter to clog with
wax crystals, restrict fuel flow, and cause loss of power. If is suggested that if fuels with cold
filter plugging points above the expected ambient temperatures are purchased, the consumer
must consult the fuel supplier and Cummins Inc. concerning fuel handling techniques. For
more information, go to Common Issues with Winter Fuel.
Ash
High ash content causes deposits of noncombustible metallic material in the combustion
chamber and on the exhaust valves.
Distillation, Maximum
Fuels with high distillation temperature can leave gummy deposits in the fuel system and
result in poor fuel combustion.
Lubricity
Fuels with low lubricity can cause increased wear or seizure of fuel system components.
Vanadium
Fuels with high vanadium content can cause valve burning.
Aluminum Fuels with high levels of aluminum can cause premature ring and liner wear, which can lead to
excessive oil consumption.
Silicon
Fuels with high levels of silicon can cause premature ring and liner wear, which can lead to
excessive oil consumption.
Sodium
Fuels with high levels of sodium can cause premature ring and liner wear, which can lead to
excessive oil consumption. Sodium can combine with vanadium, if present, and catalyze,
causing valve burning.
Zinc
Fuels with high levels of zinc can cause injector spray hole carboning. Do not use galvanized
pipe or fittings in the fuel system plumbing. Diesel fuel will leach zinc galvanized material.
Marine Distillate Oils
Cummins Inc. requires that diesel fuel meeting the specifications in Table 1 of this service
bulletin be used in Cummins® Marine engines. However, the possibility exists that fuel of this
quality may not be readily available in certain marine markets. The International Standards
Organization (ISO) has defined specifications for fuels called Marine Distillate Oils (MDO's),
including distillate fuels in category ISO-F. This category consists of four distinct fuels; DMX,
DMA, DMB, and DMC. The characteristics of these fuels are presented in Table 3.
Cummins Inc. does not recommend the use of fuels meeting the specifications in Table
3, because some characteristics of these fuels do not meet the required diesel fuel
specifications in Table 1. However, DMX, DMA, and DMB do meet the contingency fuels
specifications listed in Table 2 and can be used as such. Additionally in some areas (such as
the European Union Territory) the sulfur content has been limited to 0.2 mass percent (2000
ppm) or less for all category ISO-F fuels. Therefore, some low sulfur DMX and DMA fuels may
meet the required diesel fuel specifications and would be acceptable for use in Cummins®
Marine engines. Low sulfur marine fuel is not available in all markets. It is the user's
responsibility to select the correct fuel.
Warranty and the use of Marine Distillate Oils in Cummins® Engines
Cummins Inc. engine warranty covers failures that are a result of defects in material or factory
workmanship. Engine damage, service issues, and/or performance issues determined by
Cummins Inc. to be caused by the use of MDO fuel are not considered to be defects in
material or workmanship, and are not covered under Cummins Inc. engine warranty.
Table 3: Marine Fuel Characteristics
Characteristics Limit Category ISO-F Test Method Reference
DMX DMA DMB DMC
Appearance Visual - - - - - -
Density at 15°C, kg/m 3 Maximum (1) 890 900 920 ISO 3675 or ISO 12185
Viscosity at 40°C, centistokes Minimum 1.40 1.50 - - - - - - ISO 3104
Maximum 5.50 6.00 11.0 14.0 ISO 3104
Flash Point, °C Minimum 43 60 60 60 ISO 2719
Pour Point (upper), °C (2)
Winter quality Maximum - - - -6 0 0 ISO 3016
Summer quality Maximum - - - 0 6 6 ISO 3016
Cloud Point, °C Maximum -16 (4) - - - - - - - - - ISO 3015
Sulfur, mass % (3) Maximum 1.0 1.5 2.0 2.0 ISO 8754 Cetane Number Minimum 45 40 35 - - - ISO 5165
Carbon Residue (micro method), mass %
10% (volume) distillation, bottoms Maximum 0.30 0.30 - - - - - - ISO 10370
Carbon Residue (micro method), mass % Maximum - - - - - - 0.30 2.50 ISO 10370
Ash, mass % Maximum 0.01 0.01 0.01 0.05 ISO 6245
Sediment, mass % Maximum - - - - - - 0.07 - - - ISO 3735
Total Existent Sediment, mass % Maximum - - - - - - - - - 0.10 ISO 10307-1
Water, volume % Maximum - - - - - - 0.3 0.3 ISO 14597
Vanadium, mg/kg Maximum - - - - - - - - - 100 ISO 14597
Aluminum plus silicon, mg/kg Maximum - - - - - - - - - 25 ISO 10478
In some geographical areas, there may be a maximum density limit.
Purchasers recommended to make sure that this pour point is suitable for the equipment on
board, especially if the vessel operates in both the northern and southern hemispheres.
1.0 mass percent = 10,000 ppm.
This fuel is suitable for use without heating at ambient temperatures down to -15°C.
Power Loss
This section gives guidelines on power loss to be expected when using recommended or
contingency fuels, or fuels that are above normal temperature.
NOTE: The values given concerning power loss due to the use of contingency fuels are
intended only to help estimate power loss. Power loss can vary greatly, depending on
operating conditions, engine type, fuel system type, fuel composition, and other factors. These
guidelines can not be used to precisely calculate engine power loss.
The use of contingency fuels can cause a decrease in the power output of the engine due to
differences in fuel density and viscosity. In addition, changes in fuel temperature also affect
engine power output, because temperature affects both viscosity and density.
Density
All engines will have a predictable variation in power output, depending on the density of the
fuel used. Engines using fuels with a high density will produce more power than those using
fuels with a lower density, because the thermal energy content of the fuel is higher. Since fuel
is marketed by volume, lower density fuel carrying less thermal energy results in a
proportional decrease in fuel economy or power output.
Viscosity
In general, lower viscosity results in lower power, due to increased internal leakage in the fuel
system. Also, lower viscosity fuels generally have lower thermal energy content. The effect
viscosity has on power depends on the type of fuel system used.
Temperature Temperature causes changes in engine power because it affects both viscosity and density.
An increase in fuel temperature will cause a decrease in viscosity, which will reduce power
due to internal leakage in the fuel system, as described above. The maximum recommended
fuel pump inlet temperature for Cummins® engines is 70°C [158°F].
An increase in fuel temperature will also cause a decrease in fuel density (increase in API
gravity), which will reduce power due to lower energy content of the fuel. On Cummins®
engines using the PT™, Quantum™, or HPI fuel systems, the power loss due to increasing
temperature is less than that on engines using the in-line, distributor, or CELECT™ systems
(less than 1 percent per 5°C [10°F]), due to the inherent viscosity compensating
characteristics of these systems.
Component Wear and Durability
This section shows the effects of contingency fuels on wear and durability of fuel systems
components.
The use of contingency fuels can affect the wear and durability of both fuel pump and injector
components within the fuel system. Many of these fuels are low in viscosity and lubricity, as
measured in the Ball On Cylinder Lubricity Evaluator (BOCLE) tests. Fuels with lubricity
values below 2300 grams are considered to have poor lubricity and can cause failure of fuel
system components. Other factors that affect wear and durability are sulfur, water, and
sediment content. High sulfur content increases wear of the fuel system components.
Abnormal quantities of water and sediment in the fuel will also cause excessive wear, as well
as other engine problems.
Hot Restarts
This section shows how contingency fuels affect the ability of the engine to restart while still
hot.
On Cummins® engines which use a distributor type fuel system, the use of contingency fuels
can cause difficulty restarting the engine while it is still hot. In addition, if excessive wear exists
in the fuel pump, the same difficulty can occur even when using fuels within the range listed in
the Required Diesel Fuel Specifications. The problem is caused by excessive leakage of fuel
around the internal components of the fuel pump. Fuel leakage becomes excessive due to the
high temperatures and low viscosity of the fuel. Excessive wear of the fuel pump components
will make the problem worse. The leakage can become so great that the pump will not
produce the fuel rate necessary to restart the engine. If this problem is encountered, it can be
corrected by using fuel which meets the specifications in the Required Diesel Fuel
Specifications section of this bulletin. If this does not correct the problem, repair or
replacement of worn fuel pump components is necessary.
Alternate or contingency fuels can cause difficulty restarting a hot engine. The hot restart
complaint can be caused by fuel burning prematurely during the first compression stroke.
Lighter alternate or contingency fuels can enter the cylinder through an open injector caused
by the thermal expansion that occurs during the heat soak after engine shutdown. The burning
fuels increase the starting cylinder pressure and increase the amount of torque needed to start
the engine. Lighter alternate or contingency fuels with lower flash points increase the
probability of fuel entering and burning in the cylinder. This issue can, on occasion, occur when using fuels that meet the required properties listed in Table 1. Various Hot Restart kits
(sometimes referred to as a Hot Start Knock kit) have been released by Cummins Inc. to
address this issue.
If this complaint is encountered, it can be corrected by using fuels which meet the
requirements in the Required Diesel Fuel Specifications section of this bulletin.
Fuel Blending
This section presents the effects of blending fuels with used and new lube oil, other fuels, and
with gasoline, gasohol, or alcohol. Biodiesel fuel blends are discussed in a separate section of
this service bulletin.
There are two different types of fuel blending processes referred to in this section. The first is
the blending of used engine lubricating oil to reduce fuel costs and to aid in disposing of used
engine oil. This section also discusses the blending of fuel and engine oil in on-highway
applications. The second is the blending of heavier fuels with lighter fuels to lower the wax
content, cloud point, and pour point, and thus improve cold weather operation. In addition, the
effects and hazards of mixing alcohol with diesel fuel are discussed.
Blending Fuel and Lubricating Oil for On-Highway Applications
WARNING
Some state and federal agencies have determined that used engine oil can be carcinogenic
and can cause reproductive toxicity. Avoid inhalation of vapors, ingestion, and prolonged
contact with used engine oil. If not reused, dispose of in accordance with local environmental
regulations.
CAUTION
Never blend more than 5 percent used lubricating oil with the fuel. Do not blend other used
oils with fuel, such as transmission fluid, gear case oil, and so forth. Additional oil blending
restrictions are outlined in this section.
Used engine lubricating oil can be blended with fuel using the Cummins® Lube Oil Blender,
Part Number 3376317 (110 volt, 60 Hz) or Part Number 3376362 (220 volt, 50 Hz). This
process can be used to supplement the fuel supply as well as provide a means of disposing of
used lubricating oil.
To blend used engine oil with fuel, follow the instructions provided with the Cummins® Lube
Oil Blender.
CAUTION
Blending fuel with lubricating oil is not allowed for Cummins® Midrange and Heavy Duty
engines equipped with exhaust aftertreatment. Oil blending on these engines will result in
engine damage and possibly cause higher emission levels.
Two rulings by the United States Environmental Protection Agency (EPA) affect the
practice of blending lubricating oil with diesel fuel in the United States. First, on
September 10, 1992, the Office of Solid Waste of the United States Environmental Protection
Agency determined that used lubricating oil was not classified as hazardous waste. In addition, the blending of used lubricating oil with diesel fuel for burning in diesel powered
vehicles was determined to be an acceptable method for disposing of used lubricating oil (57
Federal Register, R 41583, September 10, 1992). Second, beginning October 1, 1993, diesel
fuel used in motor vehicles, as defined by the EPA, in on-highway applications must contain
less than 0.055 percent sulfur by weight (Mandated in Section 211 of the 1990 Clean Air
Amendments; 57 Federal Register, P. 19535, May 7,1992). Fuel blended with lubricating oil
must also meet this specification.
Cummins Inc. provides the following guidelines for blending lubricating oil with fuel:
Engines required to use ultra-low sulfur diesel fuel (15 ppm sulfur maximum) are not allowed
to blend used lubricating oil with diesel.
Midrange and Heavy Duty engines (displacements up to 18L) are not allowed to blend used
lubricating oil with diesel fuel if the engine is equipped with an exhaust aftertreatment device,
such as an oxidation catalyst, diesel particulate filter, or SCR system.
High Horsepower engines (displacements of 18L or larger) equipped with high pressure
common rail fuel systems are allowed to blend used lubricating oil with diesel fuel up to a
maximum volume-concentration of 0.5 percent using the Centinel™ system, regardless of the
presence of an exhaust aftertreatment system.
All other Cummins® engines which do not fall in to the above categories are allowed to blend
used lubricating oil with diesel fuel up to a maximum volume-concentration of 5 percent.
The blending of new lubricating oil to raise viscosity is also permissible, and is subject to the
same restrictions previously mentioned. This helps to increase the viscosity of lighter fuels to
acceptable levels. However, if the blended fuel used in motor vehicles for on-highway
applications (as defined by the EPA) exceeds the maximum sulfur content, United States
federal law has been violated and penalties can be assessed. To be sure that blended fuel
complies with the law, the following procedure must be followed. Both the diesel fuel and
lubricating oil must have their sulfur content measured by a qualified laboratory using the
testing method specified in ASTM D2622 (American Society of Testing and Materials
Standard, or ISO 4260). Once the correct blend factor has been determined, multiply this by
the volume of fuel to be blended. The result is the amount of this oil that can be blended with
this fuel and remain within legal limits. Similar restrictions and processes must be followed
worldwide where regional or national regulations can impose such sulfur limits.
As an example, consider 50,000 gallons of fuel with a sulfur content of 0.04 percent by weight
and lubricating oil with a sulfur content of 0.5 percent by weight. Of this oil, 450 gallons can be
blended with 50,000 gallons of this fuel and remain within legal limits for sulfur content in the
United States. Margins must be allowed for measurement errors.
Blending Fuel with Fuel
Cummins Inc. recommends the use of a premium diesel fuel during winter (ambient conditions
at -7°C [20°F] or below) operating conditions. Blended fuel must meet the requirements of
Table 1. See the Additives section in this service bulletin.
In cold-weather operation, the most common method of preventing fuel waxing problems is to
dilute heavier, higher wax content fuels such as diesel number 2 (D2) fuel with lighter, lower
wax content fuels such as diesel number 1 (D1) or jet fuel. This reduces the concentration of
wax, and thereby reduces both the cloud point and pour point. Blended fuels of this nature are
more expensive to use both because they cost more and because they have a lower thermal energy content. A typical blended fuel contains 30 to 60 volume-percent light distillate fuel,
usually yielding a 3 to 7°C [5.4 to 12.6°F] drop in cloud point, and a 5 to 11°C [9 to 20°F] drop
in pour point. Lower wax content fuels must be added BEFORE wax forms to be effective.
Blending Fuel with Gasoline, Gasohol, and Alcohol
WARNING
Do not mix gasoline, alcohol, or gasohol with diesel fuel. This mixture can cause an explosion.
WARNING
Under no circumstances must gasoline or alcohol be used to dilute diesel fuel. This practice
creates an extreme fire hazard and under certain circumstances an explosive hazard.
Gasoline dilution is not an effective way to lower cloud point (20 volume-percent gasoline only
lowers cloud point 4°C [7°F] and it lowers the fuel viscosity, cetane number, and flash-point).
Alcohol dilution will increase the cloud point.
Alcohol is considered a renewable energy source. Some suppliers integrate up to 15 percent
alcohol in diesel fuel to form oxy-diesel or e-diesel. While the use of special additives
addresses some of the problems with alcohol blending in diesel fuel, Cummins Inc.
recommends against the use of such blends due to safety reasons. This kind of fuel is
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