The Cold Cranking Simulator and British Engine Cranking Studies

This paper presents a summary of studies initiated by the British Technical Council to examine the repeatability and reproducibility of cold crank simulator results obtained on European cross-graded engine oils used in gasoline and diesel engines, and also to relate the results obtained to actual cranking speeds.

The study of various components of engine cranking resistance on low-temperature starting behavior confirms that only those having oil viscosity dependence are related to temperature. Results obtained on engine startability and the cranking of used lubricants show significant increases in cranking speed as a result of fuel dilution, but show the converse for high insoluble contents (up to 10%).

An advantage in cold startability is shown for the low end of the 20W specification compared to the high, but magnitude depends very much on the individual engine. Good correlation was obtained between the cold crank simulator results and the cranking tests on the gasoline engine at +10 F and diesel engine at - 10 F, using the various selected oils, including the widely used 20W/50 multigrades.