Lube oils are a blend of base oil and additives. The basic functions of lube oils are to:

  • reduce friction
  • remove heat, and
  • suspend contaminants.

The characteristics of the base oil and the intended end use determine which additives are used to produce the final product. Some of the additives used in lube oils and their functions are:

Additive Type Function
Detergents Remove impurities to prevent residue build up on engine parts
Dispersants Prevent contaminants in the oil from clumping together
Antioxidants Retard the process of oxidation. Oxidation destroys an oil's ability to lubricate
Anti-wear Bonds to metal surfaces to create a film between moving metal parts
Friction modifier Makes oil more slippery. This reduces wear and improves fuel efficiency
Corrosion inhibitor Prevents corrosion of metal surfaces
Seal swell agent Prevents loss of fluid via gaskets
Viscosity modifier Allows the oil to adapt to temperature changes, maintain its grade and retain its lubricating effectiveness
Pour point depressant Allows oil to remain more fluid at lower temperatures
Foam inhibitor Retards the formation of foam in oil
Red dye Identification