Fuel, Oil and Coolant Specifications
DETROIT DIESEL FUEL OIL SPECIFICATIONS
All diesel engines require heavy-duty lubricating oils. Basic requirements of such oils are:
LUBRICATING QUALITY. The reduction of friction and wear by maintaining an oil film between moving parts is the primary requisite
of a lubricant. Film thickness and its ability to prevent metal-to-metal contact of moving parts is related to oil viscosity. The
optimums for Detroit Diesel engines are SAE 40 or 30 weight.
HIGH HEAT RESISTANCE. Temperature is the most important factor in determining the rate at which deterioration or oxidation of
the lubricating oil will occur. The oil should have adequate thermal stability at elevated temperatures, thereby precluding formation of
harmful carbonaceous and/or ash deposits.
CONTROL OF CONTAMINANTS. The piston and compression rings must ride on a film of oil to minimize wear and prevent cylinder
seizure. At normal rates of consumption, oil reaches a temperature zone at the upper part of the piston where rapid oxidation and
carbonization can 'occur. In addition, as oil circulates through the engine, it is continuously contaminated by soot, acids, and water
originating from combustion. Until they are exhausted, detergent and dispersant additives aid in keeping sludge and varnish from
depositing on engine parts. But such additives in excessive quantities can result in detrimental ash deposits. If abnormal amounts of
insoluble deposits form, particularly on the piston in the compression ring area, early engine failure may result. Oil that is carried up
the cylinder liner wall is normally consumed during engine operation. The oil and additives leave carbonaceous and/or ash deposits
when subjected to the elevated temperatures of the combustion chamber. The amount of deposits is influenced by the oil
composition, additive content, engine temperature. and oil consumption rate.
DETROIT DIESEL LUBRICATING OIL SPECIFICATIONS
OIL QUALITY is the responsibility of the oil supplier. (The term oil supplier is applicable to refiners, blenders, and rebranders of
petroleum products, and does not include distributors of such products.)
There are hundreds of commercial crankcase oils marketed today. Obviously, engine manufacturers or users cannot completely
evaluate the numerous commercial oils. The selection of a suitable lubricant in consultation with a reliable oil supplier, observance of
his oil drain recommendations (based on used oil sample analysis and experience) and proper filter maintenance, will provide the
best assurance of satisfactory oil performance.
Detroit Diesel Allison lubricant recommendations are based on general experience with current lubricants of various types and give
consideration to the commercial lubricants presently available.
Detroit Diesel engines have given optimum performance and experienced the longest service life with the following oil performance
levels having the ash and zinc limits shown:
API Letter Code
40 or 30 ·
40 or 30 ·
*Military Specification MIL-L-2104B is obsolete and new developed products can no longer be qualified to meet this performance
level. However, many lubricants formulated to meet the performance criteria of MIL-L-2104B/1964MS are still being marketed.
Detroit Diesel engines have given optimum performance and experienced the longest service life using MIL-L-2104B/1964MS
lubricants. The majority of MIL-L-2104B/1964MS lubricants have a sulfated ash content between 0.55 and 0.85 percent by weight.
**Supplement I oils have a history of very satisfactory performance in Detroit Diesel engines. Supplement 1oils have a relatively low
ash content. However, the Supplement I oil specification is obsolete and new products cannot be qualified to meet this performance
level. Some older formulations are still distributed and used by Detroit Diesel engine customers.
· SAE 40 grade oil has performed satisfactorily and is recommended in Detroit Diesel engines. Obviously, the expected ambient
temperatures and engine cranking capability must be considered by the engine owner/operator when selecting the proper grade of
oil. Only when the ambient temperatures and engine cranking capabilities result in difficult starting should SAE 30 grade oil be
The sulfated ash (ASTM D-874) limit of all the lubricants recommended or selected as alternates for use in Detroit Diesel engines
shall not exceed 1.000 percent by weight, except lubricants that contain only barium detergent-dispersant salts where 1.500 percent
by weight is allowed. Lubricants having a sulfated ash content between 0.55 and 0.85 percent by weight have a history of excellent
performance in Detroit Diesel engines. Lubricants having a sulfated ash content greater than 0.85 percent by weight are prone to
produce greater deposit levels in the ring belt and exhaust valve areas of the engine.