Esters are produced by reacting acids with alcohols. There is a huge range of esters produced globally for a vast range of applications. Certain Ester configurations have been found to impart beneficial properties on synthetic lubricants. The most commonly used Esters in lubricants are Diesters and Polyol Esters.
Esters are commonly used as an additive in concentrations of 5 to 25% in conjunction with Poly Alpha Olefins (PAOs) in fully synthetic motor oils in order to improve additive solubility and counteract the effect PAOs have on seals.