Influence of Friction Geo-modifiers on HTHS Viscosity of Motor Oils

Motor oil of the internal combustion engine is a means to deliver particles of friction geo-modifiers to the friction surfaces. In this case, the influence of friction geo-modifiers such an important parameter as engine oil HTHS viscosity is of practical interest. The purpose of this article is to determine the HTHS viscosity multigrade engine oils of SAE class 5W-40 with different concentrations of friction geo-modifiers on the basis of pure serpentine. The tapered bearing simulator TBS 2100E TANNAS was used to measure the viscosity of oils at shear rates 10⁶ s⁻¹. A lubricating composition was prepared using two samples of multigrade engine oils viscosity grade SAE 5W-40. The mass concentration of the friction geo-modifiers was 0.1, 0.3, and 0.5% in each sample. The friction geo-modifiers lead to insignificant decrease in HTHS viscosity multigrade engine oil of viscosity grade SAE 5W-40. The viscosity decreased on 3.5–6.5% for the analyzed samples of motor oils. Therefore, the working conditions of the bearings of the crankshaft are changed insignificantly at the introduction of the friction geo-modifiers in motor oil.