Oil additives are miscellaneous chemicals used to enhance oil performance in an engine. Some additives are added to factory-made oil, but most are treated before being packaged and shipped for sale.
Oil additives are essential for keeping up an engine's performance. Without them, oil breaks down easily and works less efficiently. Some examples of oil additives used in the manufacturing of mass market compounds include detergents for trapping impurities, rust inhibitors, antioxidants and metal deactivators. The latter create a film on metal surfaces to prevent oxidation. Aftermarket additives have been claimed to enhance used oil, but they have been heavily scrutinized by the Federal Trade Commission for making unfounded claims.