The lubricating oil covered by this specification is intended for the crankcase lubrication of reciprocating spark-ignition and compression-ignition engines used in all types of ground equipment. The specification product is intended for crankcase lubrication under all conditions of service, as defined by appropriate lubrication orders, when ambient temperatures are in the range of 5 to −55 °C. The lubrication oil covered by this specification is not to replace Grade 10W, MIL-L-2104 lubricant in areas where ambient temperatures will not be below −25 °C. In addition the lubricating oil covered by this specification is intended for use in arctic regions as an all weather (year-round) power transmission fluid for military tactical/combat ground equipment.