Distillates (petroleum), solvent- refined heavy naphthenic; Base oil — unspecified (A complex combination of hydrocarbons obtained as the raffinate from a solvent extraction process. It consists of hydrocarbons having carbon numbers predominantly in the range of C20 through C50 and produces a finished oil with a viscosity of at least 19 10^-6 m^2 .s^-1 at 40°C. It contains relatively few normal paraffins.)