Diesel Lubricant Performance in Highway Truck and City Coach Service

One experimental and twelve commercial diesel crank-case oils of various industry-accepted performance levels were evaluated in highway truck and city coach service. The oil performance parameters evaluated showed that SAE-30, M1L-L-2104B lubricants, as a family of commercial oils, gave better performance than MIL-L-2104A, Supplement 1, Series 3 or multigrade products. Multigrade oils gave very poor performance in both service applications. The results of these two related programs influenced the engine manufacturers’ decision to recommend MIL-L-2104B oils.