Measuring Viscosity

Engine oil is given viscosity classifications as determined by the SAE (Society of Automotive Engineers). Categories include SAE 20, SAE 30, SAE 40, and SAE 50. A higher number denotes higher viscosity. The ratings measure viscosity only and no other characteristic. These numbers represent the oil's viscosity at 212° F.

Viscosity can also be represented on a Winter (W) scale. Possible designations are SAE 0W, SAE 5W, SAE 10W, SAE 15W, SAE 20W, or SAE 25W. These "W" categories represent the oil's viscosity at 0° F. Once again, the higher the number, the higher the viscosity. Generally, high viscosity oils are used in warm climates to maintain an adequate "thickness" level because heat thins oils. On the other hand, low viscosity (or "W") oils are used in cold climates to maintain adequate "thinness," since cold temperature thickens oil. These single viscosity (grade) oils are typically used for specific seasons.


TOP SYSTEMS
BACK ENGINE OIL
PREVIOUS WHAT IS VISCOSITY?
NEXT MULTIGRADE OILS