TBN performance study on a test fleet in real-world driving conditions using present-day engine oils

The article describes the processes of degradation of five engine oils available from various manufacturers, but belonging to the same SAE viscosity grade. The direction and intensity of changes in Total Base Number (TBN) have been analysed. As part of the experiment, the changes in engine oils occurring during actual operation (under conditions which can be described as “harsh”, i.e. frequent starting of the engine, short distance driving, extended engine idling) have been observed. All engine oils were operated in passenger cars of a uniform fleet of 25 vehicles. Total Base Number was determined in accordance with the test method ASTM D2896. The obtained results have led to the development of a statistical model enabling to calculate average predictive values of TBN for a given mileage. Moreover, an evaluation of a FTIR spectrum of an engine oil sample was presented. For the used engine oil differentiation process, FTIR spectra were analysed in the regions 600-2000 cm−1 and 3600-3700 cm−1 for five oil sample (one from each group). The results may facilitate decision-making regarding the service life of engine oils.