Interactions of Additives and Lubricating Base Oils

Automotive lubricating oils consist of base oils and a variety of chemical additives. In this study, interactions among an antioxidant (ZDDP), a dispersant (succinimide), and a detergent (calcium sulfonate) are studied in terms of oxidation stability. Oxidation tests were conducted at 60 °C and 160 °C using the free radical titration test and the thin film oxygen uptake test respectively. Complex chemical interactions in terms of oxidation stability were found among the additives, as well as the additives with the polar species in the base oil. Optimum oxidation concentrations for some of the additives were observed. The effects of temperatures on the interaction were also described.