Evaluating 5W-20 Viscosity Grade SI Engine Lubricant for Oxidation Performance

Oxidation is essential for knowing the lubricant aging. By oxidation, metal particles in oil act as catalysts which are further accelerated by increasing the oil temperature. An experimental investigation was conducted on an indigenous developed test bench of the Maruti Suzuki K10b series engine in order to evaluate the oxidation of 5W-20 viscosity grade SI engine lubricate and its related oil thickening properties of lubricating oil. The lubricant performance characteristics were evaluated for cam lobe wear, increased viscosity, and piston deposit formation for setting the minimum performance standard for gasoline engines. The test severity was generated to match the real environment by modifying engine parameters like increased intake air temperature, increased oil sump temperature, increased piston ring end gap, and reduced sump capacity. The experimental results show the stability of lubricant with respect to the oxidation stability, change in kinematic viscosity, change in total base number (TBN), change in total acid number (TAN), and the metal wear with respect to the engine run time. This test has a strong appetite for antioxidants and base oil. Volatility of base oil is directly correlated with the increase in viscosity due to the evaporation of light base oil components and the formation of non-volatile additive components.