Engine oils are made from crude oil and its derivatives by mixing of certain other chemicals (additives) for improving their certain properties. Lubricating oil is used to lubricate moving parts of engine, reducing friction, protecting against wear, removing contaminants from the engine, act as a cleaning agent, and act as an anti corrosion and cooling agent.

Accordingly, this research effort focuses on comparative study of re-refined engine oils by acid treatment, acid/clay treatment, solvent extraction/clay treatment, and activated charcoal/clay treatment methods. Methyl ethyl ketone (MEK) was used as solvent in the solvent extraction/clay treatment method.

            Different properties of refined oil and waste oil were analysed, such as fire and flash point, pour point, specific gravity, ash content, viscosity, moisture ratio and acid value.