The document discusses the American Petroleum Institute's (API) engine oil licensing and certification system. It provides background on API, describes the voluntary program that defines and monitors performance of engine oils. The system licenses the use of API marks on oils that meet standards. The document outlines the history of API gasoline and diesel engine oil performance categories and standards. It discusses the API certification marks, current gasoline and diesel standards, and the API aftermarket audit program to ensure licensed products meet standards. The document proposes expanding the program with a new "Motor Oil Matters" campaign to educate consumers on the importance of using high-quality certified engine oils.