In 1972, AMSOIL INC. introduced AMSOIL Synthetic SAE 10W-40 Motor Oil and became the first company in the world to manufacture and market an American Petroleum Institute (API) rated synthetic motor oil recommended for 25,000 miles or one year.
Why synthetic? Because synthetic lubricants are superior to conventional petroleum lubricants. Petroleum lubes are refined from crude oil, a natural substance pumped from the earth and containing diverse chemicals. Some of the chemicals in petroleum oil are detrimental to the lubrication process and to the lubricated components. For example, some petroleum oil chemicals invite oxidation in high temperature operations. Oxidation quickly destroys lubricant integrity.