Some Effects of Crankcase Lubricant Viscosity on Engine Operation

Stricter control of crankcase - oil viscosity specifications at both low and high temperatures is needed to assure optimum engine starting performance, operating economy and durability.

The degree of improvement made by petroleum refiners in low temperature cranking and starting characteristics of a number of major brand crankcase lubricants is shown by a comparison of 1966 vs 1962 test data.

High temperature viscosity also is important because of its effects on oil economy, hydraulic valve lifter collapse and hot engine starting.