identify quality motor oils for gasoline- and diesel-powered vehicles. Oils displaying these marks meet performance requirements set by U.S. and international vehicle and engine manufacturers and the lubricant industry. More than 500 companies worldwide participate in this voluntary program, which is backed by a marketplace sampling and testing program.
An oil displaying this mark meets the current engine protection standard and fuel economy requirements of the International Lubricant Standardization and Approval Committee (ILSAC), a joint effort of U.S. and Japanese automobile manufacturers. Automobile manufacturers recommend oils that carry the API Certification Mark. See the ILSAC STANDARD FOR PASSENGER CAR ENGINE OILS chart on the next page for descriptions of current and obsolete ILSAC standards.
Gasoline engine oil categories (for cars, vans, and light trucks with gasoline engines): Oils designed for gasoline engine service fall under API’s “S” (Service) categories. See inside for descriptions of current and obsolete API service categories. Diesel motor oil categories (for heavy-duty trucks and vehicles with diesel engines): Oils designed for diesel-engine service fall under API’s “C”(Commercial) categories. See the GASOLINE ENGINES and DIESEL ENGINES charts on the next pages for descriptions of current and obsolete API service categories.
The measure of an oil’s ability to flow at certain temperatures. Vehicle requirements may vary. Follow your vehicle manufacturer’s recommendations on SAE oil viscosity.
These designations apply to oils intended for gasoline-engine cars, vans, and light trucks. Widespread use of “Resource Conserving” or “Energy Conserving” oils may result in an overall savings of fuel in the vehicle fleet as a whole.
Oils designed for diesel engine service might also meet gasoline engine service. For these oils the designation is “C” category first followed by the “S” category. “C” category oils have been formulated primarily for diesel engines and may not provide all of the performance requirements consistent with vehicle manufacturers’ recommendations for gasoline-fueled engines.
The “CI-4 PLUS” designation identifies oils formulated to provide a higher level of protection against soot-related viscosity increase and viscosity loss due to shear in diesel engines. When originally introduced, CI-4 PLUS identified CI-4 oils meeting a higher level of performance. CJ-4 oils include all CI-4 PLUS performance requirements. CI-4 PLUS appears in the lower portion of the API Service Symbol “Donut.”
The current and previous ILSAC standards and API Service Categories are listed here. Vehicle owners should refer to their owner’s manuals before consulting these charts. Oils may have more than one performance level.
For automotive gasoline engines, the latest ILSAC standard or API Service Category includes the performance properties of each earlier category and can be used to service older engines where earlier category oils were recommended.