From data generated in the laboratory and pilot plant studies a quality rerefined oil can be produced via BERC/ERDA solvent extraction and clay treatment. Some of the important processing variables that determine the quality of the finished product are temperature of solvent extraction, type of clay used, temperature and time of clay treatment, and the atmosphere under which the oil is treated with clay. Yields of 75 percent based on water-distillate-free oil can be expected at the conditions used in pilot plant operations. The oils obtained could be compounded to produce a large number of high quality lubricating products. Unlike an acid-clay process where the acid sludges pose an environmental problem, the BERC/ERDA system produces a marketable sludge.