Antioxidants counteract the degradation of the oil due to exposure to Oxygen. Anti-Oxidants protect base oils under different operating conditions such as High Temperatures, High Pressures and the presence of Impurities.
Common Antioxidants are; Hindered phenol, Aromatic amine, Sulfur compounds and Organomolybdenum Compounds. Hindered phenol and aromatic amine antioxidants are recognized as radical scavengers (primary antioxidants). Sulfur compounds are classified as hydroperoxide decomposers (secondary antioxidants). Molybdenum compounds are known as antioxidation synergists. Antioxidants with different mechanisms of function have a synergistic effect, greatly increasing the oxidation stability of the oil.