U.S. Army Evaluation of NATO Multi-graded Engine Oils

This paper discusses the United States effort in a cooperative NATO program investigating the performance characteristics of multigraded engine oils. Seven lubricants (one Grade 10W-30 oil, five Grade 15W-40 oils, and a 20W-40 oil) were evaluated using the diesel engine performance tests required for qualification of MIL-L-2104D engine oils. Two test oils (one Grade 15W-40 oil and the Grade 20 W-40 oil) met the 1G2 four-cycle diesel performance established for MIL-L-2104D specification. Three products (two Grade 15W-40 oils and the Grade 20W-40 oil) demonstrated acceptable 6V-53T, two-cycle, diesel performance. However, only the Grade 20W-40 oil showed acceptable performance in both tests.

Based on the results of the program, one conclusion is that multigraded 15W-40 and 20W-40 oils have the capability to demonstrate acceptable diesel engine performance as defined by the MIL-L-2104D engine specification. In addition, meeting requirements for either the two-cycle or the four-cycle engine test does not assure that a lubricant will demonstrate acceptable performance in both type engines. Therefore, lubricant specifications must include performance requirements for both two-cycle and four-cycle diesel engines.