Prediction of Engine Cold Cranking Performance of Motor Oils 640426
This paper discusses a program conducted to determine the best method for predicting cold engine performance of motor oils from viscometric and other physical tests. Equations were developed that related cold engine cranking results for 35 oils with corresponding 0 F viscometry data. Appreciable improvement over use of extrapolated viscosities was achieved by several equations, one for forced ball viscosities and other oil properties and one for rotational viscometer results. However, neither was accurate enough to predict closely the cold cranking performance. Better understanding of flow processes in cold engines appears essential for development of a significant, low temperature, viscometric method.