Coconut-castor oil mixture: The potential of flow to tribo-contacts of internal combustion engine at low-temperatures

Abstract

Vegetable oils are desirable alternative lubricant basestocks because petroleum products are non-regenerative and eco-unfriendly. The strong metal-surface adherence and thin-film formation abilities of vegetable oils can satisfy the tribological demand of today’s improved engine tolerances. However, their poor low-temperature activities and oxidation stability are issues of concern. This paper reports the depression of the pour point of coconut oil through binary mixture with castor oil, for lubricant in IC engines. The pour point of the lead oil is reduced from 18°C to 12°C by blending with 50% weight (wt) of castor oil, and further reduced to 3°C by treating the mixture with 8%wt of a Malaysian synthesized pour point depressant making the treated blend serviceable in the tropics as lubricant for IC engines, in terms of pour point, as studied by ASTM D97-12 method. The viscosity, and viscosity index (VI), of the blended basestock are comparable to SAE 10W-30 oil. The oxidation stability (using DSC) may meet operational conditions of IC engines when additive treated. These two oils could complement each other and prepare a good base for pour point de-pressants to reduce the pour point of coconut oil to satisfy cold-starting temperature and oxidation stability requirements for IC engines.