API ESCS-1991 Engine Service Classification System: 1991 Licensees Including Brand Products Authorized to Display the Engine Service Classification System Symbol
"FOREWORD The API Engine Service Classification System is an oil labeling program that provides a basis for selecting and recommending engine oil for both gasoline and diesel engines. By means of a Symbol@ commonly called a ""donut@"" displayed on an oil container (see cover page for an example)@ and a series of letters and numbers displayed within that Symbol@ consumers can understand the service category and performance characteristic of an engine oil. A description of the Program@ definitions and listing of approved products follow. A marketer of engine oil may apply to the American Petroleum Institute for a license to use the API Symbol. The applicant must be the marketing organization responsible for the integrity of the brand name and the product's representation in the marketplace. API may issue a license when the applicant submits the appropriate application documents including certification that each oil meets industry specifications@ signs a licensing agreement which prescribes the terms and conditions of the program and pays the prescribed fee."