TRIBOLOGICAL TESTING OF ENGINE OILS.

The aim of the work is the estimation of friction and wear in the friction nodes lubricated with engine oils: mineral, semisynthetic and synthetic, from different classes of viscosity and quality. The tribological tests of oils were compared to their rheological parameters and the scanning estimation of the surface layer of the wear defects was conducted to obtain the answer to the question whether the use of oil of reduced viscosity will protect enough the friction node against wear and will not result in increased losses to friction. The elaborated method including the tribological estimation in the sliding friction and the viscosity characteristics of engine oil, extended to FEM (Finite Element Method) modelling of experimental contact, allows to predict how the tested oils will protect the mobile nodes. Due to wear resistance in the reference temperature and because of the lowest coefficient of friction in the starting conditions and constant and low coefficient of friction in lubricity tests, it can be conducted that the synthetic oil Elf Evoloution SXR 5W-30 SL/CF will the best choice in the exploitation conditions. [ABSTRACT FROM AUTHOR]