The paper presents a technology for producing base oil by oxidizing organosulfur compounds, contained in petroleum distillates and deasphaltisates, with hydrogen peroxide in the presence of vegetable (rapeseed and castor) oils, followed by extraction of oxidates and dewaxing of raffinates. Extraction of the resulting oxidized mixture (oxidate) was carried out with N-methylpyrrolidone. The content of rapeseed oil contained in the raffinate and extract was determined. The extract solution from a medium-viscosity oil distillate was cooled to obtain a secondary raffinate represented by a sulfoxide concentrate. The secondary raffinate was used as a base oil for producing a lubricant with high tribological properties for use in heavily loaded friction units. The rapeseed oil remained in the raffinate improves its viscosity index and lubricating properties. The raw materials and obtained raffinates were analyzed to assess their physicochemical and tribological properties.