The kinetics of changes in kinematic viscosity of engine oils under similar operating conditions

Abstract

The article describes the processes of degradation of five engine oils offered by different manufacturers, but belonging to the same SAE class of viscosity. The direction and intensity of changes in kinematic viscosity measured at two temperatures (40°C and 100°C) have been analyzed. As part of the experiment, the changes in engine oils occurring during actual operation have been observed. The conditions of which can be described as “severe”, i.e. frequent starting of the engine, short distance driving, extended engine idling. All engine oils were operated in passenger cars of a uniform fleet of 25 vehicles. Kinematic viscosity was determined in accordance with the EN ISO 3104. The obtained results have led to the development of a statistical model enabling to calculate average predictive values of kinematic viscosity for a given mileage. The results may facilitate decision-making regarding the service life of engine oils.