Abstract: A multi-phase process involves physical and chemical methods to recover the oil bases of used oils. The resulting oil base meets the standards and technical specifications necessary for reuse in the formulation of lube oils, greases and alike. The process includes classifying the used oil according to its physicochemical characteristics in order to optimize the subsequent phases. Next, the used oil is subject to physical pre-treatment to remove the solids of about 20 microns, dehydrate them and extinguish the remains of light hydrocarbons. Afterwards, the used oil undergoes extraction with organic chemical solvents on specific proportions within certain pressure and temperature ranges. The output is an extract composed of the oil base, the solvents and a semi-solid precipitate containing the used oil pollutants. Next, the extract is separated from the precipitate by physical methods. Subsequently, the extract passes through another physical procedure that separates the solvents from the oil base.