Cold Starting and Pumpability Studies in Modern Engines — Results from the ASTM D02.07C Low Temperature Engine Performance Task Force Activities: Summary and Conclusions

Abstract

Based upon the engine and oil types evaluated in the Low Temperature Engine Performance Task Force activities, it was found that (i) modern, fuel injected, gasoline engine designs, on average, start at lower temperatures than older types, and starting temperatures are independent of number of cylinders, configuration or displacement; (ii) CCS viscosities correlated with engine startability, but at considerably higher viscosities than in J300; (iii) an operating safety margin was observed between cold starting and pumpability; and (iv) these modern designs generally exhibited flow-limited behaviour and had limiting MRV pumpability viscosities in the range of 71 to 131 Pa∙s with an average of approximately 93 Pa∙s. On the basis of limited testing of 5 multigrade oils in the Phase II pumpability testing, it was found that air-binding pumpability could be generated in certain engine types, under appropriate cooling/operating conditions. Air-binding was only observed when significant structure was detected in the oils.