Novel Sustainable Grease Developed From Waste Cooking Mustard Oil and Garlic Oil: A Study of Rheological and Extreme Pressure Properties

Abstract

The rheological and tribological performances of waste cooking oil (WCO)-based novel sustainable grease with garlic oil as an extreme pressure (EP) additive were examined according to the ASTM standards (ASTM D1092 and ASTM D2783) using a four-ball tester. The commercially available lithium-based grease served as a reference grease for comparing and evaluating the rheological and tribological properties of the WCO-based greases. The addition of 6% garlic oil as an EP additive increased the weld load of WCO-based sustainable grease from 1560 N to 2450 N. The average wear scar diameter of WCO-based and WCO + (GO + 6 wt%) grease is reduced by 13.87% and 19.30%, respectively, compared to that of commercial (MIDCO AP-3) grease. Furthermore, the viscosity and shear stress of WCO-based grease increased with higher thickener concentrations, achieving rheological performance comparable to commercial grease. It is envisaged that garlic oil-filled grease with WCO as base oil will not only have good lubricating properties but will also pose minimum environmental hazards.