Fuel Oil and Coolant Specifications
All diesel engines require heavy-duty lubricating oils. Basic requirements of such oils are lubricating quality, high heat
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 30 or 40 weight.
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.
SPECIFICATIONS OIL QUALITY
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
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:
Former Military and Commercial
New API Letter Code Classification
SAE Grade †
30 or 40
30 or 40
† 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 used.
ASH LIMIT The sulfated ash limit (ASTM D-874) of the above lubricants shall not exceed 1.000% by weight, except
lubricants that contain only barium detergent-dispersant salts where 1.500% by weight is allowed. The majority of
lubricants marketed under the performance levels shown above have a sulfated ash content between 0.55 to 0.85% by
ZINC CONTENT The zinc content, as zinc diorganodithiophosphate, shall be a minimum of 0.07% by weight.
RECOMMENDATIONS REGARDING THE USE OF CURRENT OIL PERFORMANCE LEVEL PRODUCTS MEETING
PRESENT MILITARY LUBRICANTSPECIFICATIONS
The petroleum industry is currently marketing engine crankcase oils that may be identified as follows:
Military or Commercial
API Letter Code Service
Comment on Application and Performance
MIL -L- 2104C
Supersedes MIL -L- 45199B (Series 3) intended for diesel service.
MIL -L- 46152
Supersedes MIL -L- 2104B intended for gasoline engine passenger cars.
Meets the Performance criteria of all industry
Detroit Diesel Allison does not have sufficient experience with any of the above described lubricants to recommend their
use. Some oil suppliers have reported satisfactory performance of the above identified products marketed by them. If an
owner/operator intends to use any of the above described products, it is recommended he obtain evidence from the oil
supplier that the lubricant has performed satisfactorily in Detroit Diesel engines. The above products may be satisfactory
for use in Detroit Diesel engines under the following conditions: