Residual oils (petroleum), clay-treated; Baseoil — unspecified; [A complex combination of hydrocarbons obtained by treatment of a residual oil with a natural or modified clay in either a contacting or percolation process to remove the trace amounts of polar compounds and impurities present. It consists of hydro-carbons having carbon numbers predominantly higher than C25 and boiling above approximately 400 °C (752 °F).]