Abstract: Engine lubricating oil is removed from the engine sump, passed through a strainer and pumped at superatmospheric pressure through a heater to raise the temperature to 150.degree.-180.degree. F., a portion of the heated pressurized oil is passed through a filter and to the oil sending unit of the engine while the remainder of the heated pressurized oil is refined by filtering to remove particles above 5 microns and to vaporize and remove vaporizable contaminants; the refined oil being returned at atmospheric pressure by gravity to the engine sump.

Abstract: System for recovering purified oil from a mixture of oil, water, and solid particles; comprising allowing the mixture to settle while heating to about 160.degree. F. to form a lower water layer and an upper oil layer; pumping off the water layer and passing it through a strainer to separate solids; pumping off the oil, passing it through a strainer to remove solids, heating the strained oil and passing it through a purification step including filtering fine solids, heating the oil to vaporize any volatile components, and separating the vapors so produced.