INFLUENCE OF THE PRIMARY AND SECONDARY OXIDATION INHIBITORS ON THE OXIDATION STABILITY OF THE MINERAL BASE OILS

Oxidation stability is one of the most important characteristics of both base oils and finished products. Based on this characteristic, it is possible to evaluate the ability of lubricants to provide a long usage time under different application conditions. In order to ensure the best possible resistance of the lubricant to oxidation, in the formulations of finished products it is necessary to add oxidation inhibitors that will protect lubricant against oxygen attacks. The rate of oxidation depends on the quality and type of the base oil, the used additive package, but also the type of oxidation inhibitor, as well as the conditions of use. The aim of this paper was to investigate the influence of primary and secondary oxidation inhibitors on the oxidation stability of mineral base oils. Two base oils of different viscosity gradations were used for the test, as well as two types of oxidation inhibitors, primary and secondary. Samples were inhibited with five different concentrations. A standard test method ASTM D 2272 was used to determine oxidation stability.