SAE, the abbreviation ofSociety of Automotive Engineers, may represent the classification of viscosity grade, for instance, SAE30, SAE40 are the one-grade oil, SAE10W-30, SAE15W-40, the multi-grade oil; “W” means winter, low temperature.

API, the abbreviation ofAmerican Petroleum Institute, may represent the classification of engine oil quality. API engine oil classification system may be divided into the following categories:

“S” series represent the oil for gasoline engine, such as SF,SG,SJ,SL,SM, etc. (the practical performance and quality level is improved progressively);

“C”series represent the oil for diesel engine, such asCD,CF,CF-4,CH-4,CI-4, etc. (the practical performance and quality level is improved progressively);S and C together represent the engine oil commonly for gasoline and diesel engine, such as SF/CD,SG/CF-4,SL/CF, etc.