The object of the invention is a process for recycling used lubricating oils. After drying and gasoline removal, the oil is distilled and then treated with sodium or sodium hydride in a finely-divided state at elevated temperature. This is followed by a further distillation. Both distillations are at temperatures below 300.degree. C., the oil fractions of low volatility being respectively distilled in a molecular distillation apparatus at below 2 mbar.