The American Petroleum Institute (API) developed a classification system to simplify the selection of motor oils for various types of engines. A lawn mower engine, a gasoline automobile engine, and a diesel truck engine have dramatically different requirements for viscosity (thickness), wear additives and change intervals. You've no doubt followed a diesel truck that was really pouring smoke
. out the stack. This is because diesel engines run on a less refined fuel than gasoline engines, which deposit more contaminants in the oil, requiring a different oil and change interval.. Every can or container of motor oil sold in the U.S. is clearly labeled with the API service code, such as "API Service SM/SL" for gasoline auto engines. Your vehicle's owner's manual is the best source of information for oil requirements and change schedule. Reputable automobile dealers, service stations and quick lube shops can generally be counted on to use the correct oil for your vehicle. You can find more information here: http://www.api.org/certifications/engineoil/categories/index.cfm
