Additives acting chemically in the lubricant mass
Lubricants - Chemically active additives

The oxidation of hydrocarbons and other lubricant constituents is the phenomenon that determines their service life, and as soon as the operating temperature exceeds 50-60°C in continuous use and in air, the use of antioxidant additives becomes indispensable.

Consequently, with the exception of a few rare cases (lubricants for lost lubrication, release lubricants, lubricants for very low temperatures), virtually all lubricants contain antioxidant additives. Also known as "oxidation inhibitors", they slow down the oxidation process, depending on how they affect the various stages of the oxidation reaction.