Reconstituting lubricating oil

摘要

A used lubricating oil comprising lube oil additives, including zinc dithiophosphate is reconstituted. Zinc dithiophosphate is thermally decomposed at a temperature of 400 DEG F. (204 DEG C.) to 1000 DEG F. (538 DEG C.) for a residence time of 10 to 120 minutes. The resulting oil is subjected to vacuum distillation. A zinc-free (i.e. ash free by ASTM D-482) oil is stabilized by catalytic hydrogenation or clay treating to produce a lubricating oil blending stock. About 5 to 25 vol % is recovered as a metal containing bottoms product, useful as asphalt extender. The process is carried out in the absence of chemical demetallizing.