Tribological properties of polyol ester - commercial motorbike engine oil blends

Abstract This current study investigates the effect of blending bio-lubricant with commercial lubricant on physico-chemical and tribological properties. The synthesis of TMP and PE ester are optimized to obtain 100 % long chain tetra-esters and extreme care was taken during preparation of bio-lubricant to lessen deterioration of physio-chemical properties by blending with commercial oil. SM grade commercial petrol engine oil was blended with Tri-methylolpropane (TMP) ester, Penta-erythritol (PE) ester derived from Calophyllum-inophyllum in 10, 15, 20 and 25 % v/v. The tests for anti-wear, anti-friction and extreme pressure propertiesare conducted on the sample oils on a four-ball wear tester. The friction coefficient and wear of bio-lubricant –commercial oil blends have decreased significantly up to 20 % blending percentage. In the extreme pressure test, there is a substantial improvement in the weld load and marked improvement in the load wear index signifying the better load-bearing capacity of commercial oil – bio-lubricant blends. A synergy between bio-lubricant and additives in the commercial oil was found from a metallographic examination of worn balls after the EP test. The optimum volume percent of blend was found to be 15 % PE blend and 10 % TMP blend for optimum overall performance.