Investigation of Mixture of Vegetable Oil and Synthetic Esters as Environmentally Friendly Base Stock for Low-temperature Lubrication Applications

Environmental issues are of great importance in all the areas of industry and transport. Usage of environmentally friendly, easily biodegradable lubricants has a benefit, when the oil can get into environment by using total loss lubricants, leakages or some accidents. Due to inherent biodegradability, extremely high viscosity index, lubricity, and low cost various vegetable oils are used to produce environmentally friendly lubricants. However vegetable oils have some drawbacks, in particular narrow temperature range and poor oxidation stability. The aim of current study is to evaluate possibility to improve vegetable oil cold temperature properties by dilution it with synthetic esters. The dilution of rapeseed oil is done up to 30 % by lower viscosity poly alpha olefins. The pure point, low temperature flow behavior and tribological properties of diluents are investigated. The results show significant improvement in pure point temperature and low temperature flow ability. Dilution has negative effect on tribological properties. However the investigated mixtures are compatible with antiwear additives and their tribological properties can be improved.