Series 638 – Section 5.1 Fuel

Section 5.1

The quality of fuel used is a very important factor in obtaining satisfactory engine performance, long engine life, and acceptable exhaust emission levels. The Turbotronic 638 engine was designed to operate on most diesel fuels marketed today. In general, fuels meeting the properties of ASTM Designation D 975 (low sulfur grades 1-D and 2-D) have provided satisfactory performance. The ASTM D 975 specifications, however, will not in itself adequately define the fuel characteristics required for assurance of fuel quality. The properties listed in Table "Diesel Fuel Specifications" provide maintenance free operation and optimum engine performance. For a complete description of these properties refer to Detroit Diesel Corporation publication 7SE270, Lubricating Oil, Fuel, and Filters ; engine requirements.‪

General Fuel Classification


No. 1-D

No. 2-D

API Gravity, 60 ° F*‪

D 287‪

40 - 44‪

34 - 38‪

Specific Gravity, 60 ° F *‪

D 1298‪

0.806 - 0.825‪

0.835 - 0.855‪

Flash Point, Minimum - ° C‪

D 93‪



Viscosity, Kinematic - cSt @ 40 ° C‪

D 445‪

1.3 - 2.4‪

1.9 - 4.1‪

Sulfur Content, Maximum - wt%‪

D 2622‪



Cloud Point ° F ( ° C)[‪

D 2500‪

See Note]‪

See Note]‪

Cetane Number, Minimum*[‪

D 613‪



Cetane Index, Minimum[‪

D 4737‪



Distillation Temperature, ° C ( ° F)[‪


- IBP, Typical*‪


350 (177)‪

375 (191)‪

- 10% Typical*‪


385 (196)‪

430 (221)‪

- 50% Typical*‪


425 (218)‪

510 (256)‪

- 90% Maximum*‪


500 (260)‪

625 (329)‪

- 95% Maximum*‪


550 (288)‪

671 (355)‪

Recovered Volume, % Minimum*‪




Water & Sediment, Maximum - wt%‪

D 2709‪



Ash, Maximum - wt%‪

D 482‪



Carbon Residue on 10%, Maximum - wt%‪

D 524‪



Copper Corrosion, Maximum‪

D 130‪

N0. 3‪

No. 3‪

Accelerated Storage Stability, Maximum *‪

D 2274‪

15 mg/L‪

15 mg/L‪

Dupont Pad Test, Rating Maximum*‪




Lubricity, gm, minimum‪

D 6078‪



Table 1. Diesel Fuel Specifications

Note: * Not Specified in ASTM D 975

Note: [Differs from ASTM D 975

Note: ]The cloud point should be 10°F (6°C) below the lowest expected fuel temperature to prevent clogging of fuel filters by wax crystals

Section 5.1.1
Biodiesel Fuel

Biodiesel fuels may be produced from a wide variety of sources and may be used in all DDC engines provided they are derived from soy methyl ester (SME) and rape methyl ester (RME) and are blended to a maximum of 20% by volume in diesel fuel. The resulting blend must meet the properties listed in Table "Diesel Fuel Specifications" , ” Diesel Fuel Specification Chart".‪

Although such blends purport to reduce exhaust emission particulates, they increase engine exhaust nitrogen oxides content. They also tend to have poorer thermal stability and may deteriorate engine oil TBN more rapidly than wholly petroleum based diesel fuels. Use of these fuels may require a reduction in oil drain interval. These fuel blends have not been fully evaluated relative to diesel fuel system durability or engine oil effects.‪

Section 5.1.2
Premium Diesel Fuel

Several oil companies market fuels they designate as "premium" diesel fuel. This fuel will typically have a higher cetane number and lower density than ASTM D975 2D fuel. These fuels will also have a performance additive package. Although premium diesel fuels are not covered by any existing industry specification, they may be used in DDC engines. It is recommended that the customer obtain additional information from the fuel marketer and compare properties to those listed in Table "Diesel Fuel Specifications" , Diesel Fuel Specification Table, before using.‪

Section 5.1.3
Fuel Additives

Detroit Diesel engines are designed to operate satisfactorily on a wide range of diesel fuels. The regular use of supplemental fuel additives is not required or recommended. Some additives may be beneficial in addressing temporary fuel quality problems but should not replace proper fuel selection and handling.‪

Section 5.1.4
Fuel Cleanliness

Fuel should be clean and free of contamination. Storage tanks and stored fuel should be inspected regularly for dirt, water, or water-emulsion sludge, and cleaned if contaminated. Storage instability of the fuel can lead to the formation of varnish or sludge in the tank. The presence of these contaminants from storage instability must be resolved with the fuel supplier. If fuel is stored on site, the following is recommended:‪


Do not use a fuel storage tank or lines made from galvanized steel. The fuel will react chemically with the galvanized coating to form powdery flakes that will quickly clog fuel filters and cause damage to the fuel pump and injectors.‪

  • Keep the storage tank filler cap covered to prevent contamination by rain water.
  • Keep the tank clean, especially around the filler cap and tap areas.
  • Position the tank so that it tilts slightly toward the bottom drain. This will make it easier to drain accumulated water and sediment.
  • Minimize condensation by keeping the tank reasonably filled at all times.
  • After filling the fuel storage tank, wait a few hours before filling equipment tanks. This will allow contaminants to settle.

Where water contamination is a concern, the fuel system should be equipped with a fuel/water separator which should be serviced regularly. In environments where microbe growth is a problem, a fungicide such as Biobor JF (or equivalent) may be used. Microbial activity may be confirmed with commercially available test kits. Follow the manufacturer's instructions for treatment. Avoid the use of fungicides containing halogenated compounds, since these may cause fuel system corrosion.‪

When small amounts of water are present, supplemental additives containing methyl carbitol or butyl cellusolve are effective. Follow the manufacturer's instructions for their use. The use of isopropyl alcohol is not recommended due to its negative effect on fuel lubricity.‪

  • Used Lubricating Oil:

    Detroit Diesel specifically prohibits the use of drained lubricating oil in diesel fuel. Used lubricating oil contains combustion acids and particulate materials which erode injector components, resulting in loss of power and increased exhaust emissions. In addition, the use of drained lubricating oil will increase maintenance requirements due to filter plugging and combustion deposits. Refer to the section on "Waste Oil Disposal and Rerefined Oils" for recommendations on proper used oil disposal‪

  • Gasoline:

    The addition of gasoline to diesel fuel will create a serious fire hazard. The presence of gasoline in diesel fuel will reduce fuel cetane number and increase combustion temperatures. Tanks which contain such mixtures should be drained and cleaned as soon as possible.‪

Detroit Diesel Corporation will not be responsible for any detrimental effects which it determines resulted from the use of used lubricating oil or gasoline in the diesel fuel.‪

Section 5.1.5
Cold Weather Operation

In cold weather, diesel fuel will form wax crystals that can restrict flow and clogfilters. Fuel suppliers approach this problem several ways. Some provide a speciallyrefined product while others may use flow improving additives or winter blends. Winter blended fuel will likely contain kerosene or 1-.D fuel which provides good cloud point temperatures but will result in a lighter fuel with a lower heat content. The use of such fuels is acceptable but may result in reduced engine power and/or fuel mileage.‪

Section 5.1.6
Using Drained Lubricating Oil in Diesel Fuel

The disposal of waste oil is a serious environmental concern, best addressed by the engine oil supplier, who should accept responsibility for proper disposal of this material as part of the business of providing lubricant.‪


Detroit Diesel does NOT recommend blending engine drain oil into diesel fuel. Such practice will adversely affect exhaust emissions, and will likely result in damage to the fuel injection system and the formation of excessive combustion deposits.‪

Detroit Diesel will not be responsible for any detrimental effects that it determines result from this practice.‪

Series 638 Service Manual - 6SE648
Generated on 10-13-2008

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