Results of tribological research of mineral motor oil with and without twisted nematic liquid crystal additive (stearic acid cholesteryl ester) are presented in the article. Experimental research was performed by means of a “fixed segment – rotating roller” tribometer according to the central three-factor second-order rotatable factorial design. The following parameters were accepted as controllable factors: contact pressure (3.32–6.68 MPa), concentration of liquid crystal in lubricant (0.16–1.84 ) and the average height of surface roughness of contacting surfaces of roller and segment (2.5–37.5 μm). The friction coefficient and friction zone temperature were served as output parameters. Regression equations describing the friction process were obtained and tribological efficiency of liquid crystal additive was established.