include eleven military specifications for engine oils. Although ten are obsolete, they are still commonly used to designate required engine oil performance levels. To qualify under a military specification, an oil must meet minimum requirements in laboratory engine tests. In most cases these are the same ASTM tests used to define API Engine Service Categories. The following is a listing of the military specifications and API Service equivalents for engine oils in order of ascending quality (the API service equivalents of obsolete military specifications remain valid):

Mil. Spec	Description
MIL-L-2104A (API CA)	Obsolete, superseded by MIL-L-2104B; describes an oil type still used by some fleet owners for older, less critical equipment.
MIL-L-2104A Supplement I (API CB)	Obsolete; describes oil type similar to MIL-L-2104A, but tested under more severe conditions.
MIL-L-2104B (API CC)	Obsolete, superseded by MIL-L-46152, but still widely used as a standard.
MIL-L-46152C (API SF-CC)	Obsolete, superseded by MIL-L-46152D; meets requirements for gasoline engines and moderate duty diesel engines.
MIL-L-46152D (API SG)	Obsolete, superseded by MIL-L-46152E; incorporates APISG engine test requirements.
MIL-L-46152E (API SG)	Obsolete, applies only to SAE 5W-30, 10W-30, and 15W-40; incorporates API SG engine test requirements plus high-temperature/high-shear viscosity and ASTM D 2887 evaporation loss limits.
MIL-L-45199B (API CD)	Obsolete, superseded by MIL-L-2104C; the specification is essentially the same as the Series 3 specification established by Caterpillar Tractor Company.
MIL-L-2104C (API CD)	Obsolete, superseded by MIL-L-2104D; covers the addition of new heavy trucks, tanks, and other tactical military vehicles, and includes gasoline engine performance level between API SC and SD.
MIL-L-2104D (API CD)	Obsolete, superseded by MIL-L-2104E; covers the addition of new engine test requirements and a revision of the viscosity grades that can be approved. Gasoline engine performance is between API SD and SE.
MIL-L-2104E (API CD)	Obsolete, superseded by MIL-L-2104F; this change reflects the substitution of the Sequence IIIE and VE tests for the older Sequence IIID and V-D; however, gasoline engine performance requirements are unchanged, remaining between API SD and SE.
MIL-L-2104F	Supersedes MIL-L-2104E; includes the Sequence IIIE, L-38, Caterpillar 1K, Detroit Diesel 6V92TA and Mack T-7 tests; currently, no API Category fully meets the requirements of this military specification.