1. Main types of lubricant additives

Lubricant additives are differentiated according to their intended purpose:

• to prevent undesirable changes due to tampering in service. These are the inhibitors;

• to improve the initial properties of the base oil. These are called improvers.

They can also be classified according to their very general mode of action. We distinguish between :

• those which act chemically in the lubricant mass, limiting oxidation (oxidation inhibitors) or neutralizing acid pollutants (overbased detergents);

• those that act chemically on surfaces, protecting non-ferrous metals against acid corrosion (passivating and deactivating anticorrosives), preventing adhesive wear and its ultimate form, surface seizure, forming...