API stand for American Petroleum Institute. Motor oil used for vehicle engines is commonly called engine oil in American Petroleum Institute (API) documentation. Engine oil is used for the lubrication, cooling, and cleaning of internal combustion engines. Motor oil may be composed of a lubricant base stock only in the case of non-detergent oil, or a lubricant base stock plus additives to improve the oil's detergency, extreme pressure performance, and ability to inhibit corrosion of engine parts. Lubricant base stocks are categorized into five groups by the API. Group I base stocks are composed of fractionally distilled petroleum which is further refined with solvent extraction processes to improve certain properties such as oxidation resistance and to remove wax. Group II base stocks are composed of fractionally distilled petroleum that has been hydrocracked to further refine and purify it. Group III base stocks have similar characteristics to Group II base stocks, except that Group III base stocks have higher viscosity indexes. Group III base stocks are produced by further hydrocracking of Group II base stocks, or of hydroisomerized slack wax, (a byproduct of the dewaxing process). Group IV base stock are polyalphaolefins (PAOs). Group V is a catch all group for any other synthetic and mineral base stocks. Examples of group V base stocks include polyol esters, polyalkylene glycols (PAG oils), and perfluoropolyalkylethers (PFPAEs). Groups I, II, and III are sometimes referred to as mineral oils and groups IV and V as synthetic oils. However, most manufacturers have labeled their group III based oils as synthetic in the US for reasons of economy and marketing. Motor oils are further categorized by their API service class. The API service classes have two general classifications: S for Service (typical passenger cars and light trucks using gasoline engines) and C for commercial applications (typical diesel equipment). Note that the API oil classification structure has eliminated specific support for wet-clutch motorcycle applications in their descriptors, and API SJ & newer oils are referred to be specific to automobile and light truck use. The latest API service standard designation is SM for gasoline automobile and light-truck engines. The SM standard refers to a group of laboratory and engine tests, including the latest series for control of high-temperature deposits. Current API service categories include SM, SL and SJ for gasoline engines. All previous service designations are obsolete, although motorcycle oils commonly still utilize the SF/SG standard. There are seven diesel engine service designations which are current: CJ-4, CI-4, CH-4, CG-4, CF-4, CF-2, and CF. All others are obsolete. It is possible for an oil to conform to both the gasoline and diesel standards. Engine oil which has been tested and meets the API standards has the API starburst symbol with the service designation on containers sold to oil users. The latest guide to API oil certifications can be found at . The International Lubricant Standardization and Approval Committee (ILSAC) also has standards for motor oil. Their latest standard, GF-4 was approved in 2004. A key test is the Sequence IIIG  , which involves running a 3.8L, GM 3.8L V-6 at 125 horsepower, 3600 rpm, and 150°C oil temperature for 100 hours. These are much more severe conditions than any passenger car would see: cars typically average a few dozen horsepower and 80°C. The IIIG test is about 50% more difficult  than the previous IIIF test, used in GF-3 and API SL oils. Engine oils bearing the API starburst symbol since 2005 are ILSAC GF-4 compliant.  The ACEA A3/A5, and MB 229.5 tests used in Europe are even tougher, it is debatable whether this matters for normal drain intervals (5,000-7,000 miles). CEC (The Co-ordinating European Council) is the development body for fuel and lubricant testing in Europe and beyond, setting the standards via their European Industry groups; ACEA, ATIEL, ATC and CONCAWE. The Japanese Automotive Standards Organization (JASO) has come up with their own set of standards for 4-stroke gasoline motorcycle engines (JASO-MA), for 4-stroke automotive engines (JASO-MB) and 2-stroke gasoline engines (JASO-FC). These standards, especially JASO-MA and JASO-FC are designed to address oil-requirement issues not addressed by the API service categories.