Lubricant Requirements of an Advanced Designed High Performance, Fuel Efficient Low Emissions V-6 Engine

Modern high power density gasoline fueled engines place an ever-increasing demand on the engine lubricant. In this study, it is shown that advances in engine design to increase performance, improve fuel economy and lower emissions have outpaced the development of typical commercial engine lubricants. Advanced designed engines began to experience oil starvation as a result of a combination of driving cycles, oil quality and poor maintenance practices. The cause was traced to excessive increases in borderline pumping viscosity as measured by MRV TP-1 (ASTM D4684). Used oil analysis for MRV TP-1 showed viscosity greatly increased in excess of stay-in-grade requirements and in many cases the crankcase lubricant was solid at the temperature appropriate for its viscosity grade. However, at the same time CCS values were in grade or only slightly (1W grade) elevated. An investigation examining used oil showed high levels of oil oxidation and nitration to be the primary forces at work in degrading the engine lubricant. Formulating solutions were investigated and the outcome of that work will be discussed. An aggressive field trial was conducted to show proof of performance of the optimized reformulated engine lubricants and the results are presented. Finally, there is discussion of further work to be conducted and a proposal for a new sequence test to address oxidation, nitration, piston deposits and pumpability for the next ILSAC category (GF-4).