Study of Dependence of Kinematic Viscosity and Thermal-Oxidative Stability of Motor Oils

The results of the study of thermo-oxidative stability of mineral and synthetic motor oils in the temperature range from 170 to 200 degrees C are presented. The indicators of thermo-oxidative resistance are proposed, taking into account optical density, evaporation, and kinematic viscosity. It should be noted that, as an indicator of thermo-oxidative resistance, three variants of a combination of optical density, evaporation coefficients, and relative viscosity were considered. The effect of temperature on the oxidation processes was investigated, and an analytical relationship between optical density, evaporation, and kinematic viscosity was obtained. It is established that the oxidation of mineral oil produces two types of products regardless of the oxidation temperature, which is confirmed by the presence of a branch of dependence with a high rate of change in optical density. It has been established that the change in kinematic viscosity during the oxidation of mineral and synthetic oils occurs according to a general U-shape, regardless of temperature.