The most important petroleum fraction is lubricating oil that is used in almost all vehicles and machines. After running of thousand kilometers, a vehicle needs to change the lubricating oil it was using because of impurities and contaminants in the base oil. This contamination contains unsaturation, phenolic compound, aldehyde, acidic compound, additive, metals, varnish, gums and other asphaltic compounds originating from the overlay of bearing surfaces and degradation of the base oil components. Even if impurities dominate on the waste oil, most of the base oil part in the waste oil is not exhausted. This thesis work studies refining of used engine oil with a solvent extraction followed by adsorption process. Factors of the experiment for solvent extraction method were Oil to solvent ratio (1:1, 1:3, 1:5) and types of solvents (methanol, ethanol and the composite of the two solvents at different ratios). The used motor oil (total Rubia) was collected from local garage and treated with a series of pretreatment methods (sedimentation, filtration, dehydration, solvent extraction and solvent stripping steps). Finally, adsorption process was applied. The refined oil was characterized and compared with the waste oil based on the measured property of density, viscosity, flash point, ash content and other parameters. Solvent ratio on the refining process had a significant effect on the experimental responses like sludge removal, ash content and density. Maximum sludge removal was recorded on oil which was extracted by methanol with 1:3 and 1:5 oil-solvent ratio. Methanol had the highest sludge removal efficiency than ethanol solvent and composite solvents due to its higher solubility. Similarly, density and ash content were seen to be decreased as solvent ratio on oil increased (high on methanol) since sludge removal increases. The solvent-treated oil was further purified by adsorption process considering factors of adsorbent dosage and temperature. Both temperature and adsorbent dosage showed significant effect on %removal of metals. Adsorbent dosage of 2.5g per 50 ml of solvent extraction treated oil exhibited as the highest % removal of metals (99%) at 60 o C. Therefore, it can be concluded that solvent extraction followed by adsorption process is an effective method to recycle used engine oil for both economic and environmental protection purposes.