Internationally, there is no precise definition of synthetic oil versus mineral oil, it is a common term, API (American Petroleum Institute) has five categories of base oil, usually the third and fourth category of base oil is called synthetic oil. The usual synthetic oils are: PAO, XHVI, and esters.

Base oil types are divided into five categories as follows.The first category, conventional solvent-refined mineral oils.The second category, hydrocracked mineral oils.Category III, highly hydrocracked or hydroisomerized waxes.Fourth category, polyalpha-olefins (PAO).Category V, other synthetic oils