The dexos approved oil list is an accurate oil reference for General Motors model vehicles only. All oils on the list have been tested and approved by General Motors for use with GM automobiles.
Dexos approved oil is certified for use with GM vehicle brands including Chevrolet, Buick, GMC, Cadillac and others. The Duramax diesel is the only GM vehicle model not compatible with dexos oil, as it requires API CJ-4 engine oil. As of 2015, dexos approved oils are not tested for use with non-GM vehicles.
Two types of dexos certifications exist: dexos1 and dexos2. The dexos1 certified oils are intended for use with gasoline engines, while dexos2 certified oils are designed for light-duty diesel engines.