Vol. 7, Issue 2, Part C (2025)

In this article, we have determined four rheological models that describe the behavior of MC20W50 oil. These models faithfully describe the non-Newtonian behavior of the oil because they have correlation coefficients close to unity. This study investigates the rheological behavior of MC 20W50 multigrade oil, mainly used for the lubrication of internal combustion engines. The analysis was performed using an Anton Paar MCR 302 rotary rheometer, in a temperature and shear controlled regime. The results revealed a significant dependence of the viscosity on temperature, with the oil showing a non-Newtonian behavior at low temperatures, and a near-Newtonian behavior at high temperatures. The viscosity curves as a function of the shear rate indicate a slight pseudoplasticity at low temperatures, which suggests a good adaptability in cold start conditions. In conclusion, MC 20W50 oil demonstrates good rheological stability and adaptive performance in a wide range of thermal and mechanical conditions, which recommends it for use in variable operating regimes.