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What Is SAE 5W-30?

by Christopher John

SAE 5W-30 is a specific kind of motor oil. The letters and numbers show that the oil meets certain standards and convey specific attributes of the oil.


SAE stands for the Society of Automotive Engineers, an organization that sets the temperature requirements used to rate oils. The SAE designation shows that the oil meets those requirements, which allow the engineering standards of the motor oil to be uniform.

Viscosity Rating

"W" stands for Winter, and it shows that the oil meets the low-temperature requirements of the SAE, which is at 0 degrees Fahrenheit. The "5" is the oil's cold-weather viscosity rating, which shows how thick or thin the oil is when you try to start an engine at cold temperatures. The "30" shows the oil's viscosity rating at the SAE's high-temperature requirement, set at 212 degrees Fahrenheit.

Viscosity Differences

A 5W oil is the usual choice for winter use because it has less viscosity, or thickness, in the cold than 10W oil, and will flow easier through the moving parts of a vehicle engine. 5W-30 has less viscosity in both cold and hot weather than a 10W-40 oil. Be certain to use the oil viscosity that is called for by your vehicle owner's manual.

About the Author

Christopher John has been a freelance journalist since 2003. He has written for regional newspapers such as "The Metro Forum" and the "West Tennessee Examiner." John has a Bachelor of Arts in journalism from Memphis State University.

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