The SAE grade number indicates the viscosity of the engine oil, or its ability to lubricate under a given temperature. The lower the SAE grade number, the lighter the oil; the lower the viscosity, the easier it is to crank the engine in cold weather.
The API (American Petroleum Institute) designation indicates the classification of engine oil for use under given operating conditions. Only oils designated for Service SG should be used to provide maximum engine protection. Both the SAE grade number and the API designation can be found on the container.
NOTE: Non-detergent or straight mineral oils should not be used.
Oil viscosities should be chosen from those oils recommended for the lowest anticipated temperatures during the oil change interval.