The diagnostic and operating criteria as well as the environmental protection impose very diversified requirements on the parameters of work of car engine oils in the area of lubricity and rheological properties. The aim of the work was the estimation of resistance to wear of the elements lubricated with these oils working at sliding friction as well as the estimation of rheological parameters of the oils in the reference temperature and in sub-zero and low temperatures at controlled shear stress. The tested materials included mineral engine oils, semisynthetic and synthetic ones that belong to different viscosity classes. Wear defects were determined with the use of the four-ball testing machine and also the characteristics of viscosity were described with the help of the rotational rheometer. On the basis of the results of the tests, in accordance with the elaborated method it is possible to compare oils designed for application and, at the same time, diagnose the way in which they will secure motive nods in the conditions of operation.