Understanding Cold Crank Simulator Viscosity
The COLD CRANK SIMULATOR (CCS) Viscosity Test is used to determine the internal fluid friction in motor oils with a “W” grade designation. This test is calculated in cP units as well, and measures the amount of energy required to overcome the resistance present in a lubricant that has been collected at temperatures from 23 ° F (-5 C) to as low as -31 ° F (- 35 ° C), depending upon the anticipated SAE “W” classification of the oil being tested. Performance requirements to meet SAE “W” grades are outlined in the SAE J-300 engine oil viscosity classifications.
Cold Crank Simulator Viscosity Test Procedure
The CCS Viscosity Test simulates an engine’s ability to turn over at cold temperatures. Gauges monitor rotations per minute (rpm), amperage draw, and motor input. A universal motor is run at a constant voltage to drive a rotor, which is closely fitted inside a stator and immersed in the test oil. The viscosity of the oil at the given test temperature determines the speed of the rotor and amperage draw; Thicker oil results in slower speed and more amperage drawn. Speed and amperage drawn are then converted to centipoise.
CCS Viscosity Numbers Explained
Like the Brookfield Viscosity Test, CCS results showing a lower cP number Indicate lower viscosity. Oils that are thicker at low temperatures (high cP number) tend to exhibit more resistance and require more energy to pump and circulate and display a higher cP number on the CSS test. A higher cP number at a given temperature is directly correlated to a greater amount of energy required to turn an engine over, and it also indicates a greater potential for starting difficulties. Most importantly, CCS results suggest a lubricant’s ability to be circulated at a given temperature and its ability to provide wear protection.