Motor oil

Fluid 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 catergorized into five groups by the American Petroleum Institute (API). Groups I and II are composed of fractionally distilled petroleum. Group III base stock is composed of hydrocracked and distilled petroleum. Group IV base stock is composed of polyalphaolefins (PAOs). Group V is a catch all group for synthetic base stocks. Examples of group V include polyol esters, polyalkalene glycols (PAG oils), and perfluoropolyalkylethers (PFPAEs). Groups I, II, and III are conventionally referred to as mineral oils and groups IV and V as synthetic oils, however certain aggressive marketers have recently labeled group III based oil as synthetic in the US. Caveat emptor. Motor oils are further categorized by their viscosity ratings and API service class.

Petroleum