Definition of High-Temperature Use Limits for MIL-L-2104 Engine Oils

The high-temperature use limits for military and commercial diesel engine oils were found to be engine specific. With respect to oil properties such as viscosity grade and volatility, the two-cycle 6V-53T engine with trunk- type pistons was the most sensitive of the three engines that Belvoir Fuels and Lubricants Research Facility SRI investigated. Catastrophic engine distress is probable if certain oils are used at increased operating temperatures in this engine. Operation of the 6.2L engine at increased temperatures caused oil degradation. Oil thickening from oxidation and soot accumulation was observed as was TAN increase. While the oil degraded substantially in the 6.2L engine, overall engine operation continued with no apparent problems. Long-term wear problems would be expected if the engine continued operation using the highly acidic and very viscous degraded oil. However, the VTA-903T engine was not sensitive to the oil used, and oil degradation at increased temperatures was fairly mild. Unfortunately, operation of the VTA-903T engine at increased temperatures was limited by engine hardware problems that were not lubricant related. Diesel engine oil, TAN, MU-L-2104 Diesel engine, 6V-53T, Oil oxidation, 6.2L, High temperature, VTA-903T