Dewaxing with selective solvents at low temperatures is unavoidable in production of lube ils from paraffin-base crude oils. A mixture of acetone or methyl ethyl ketone (MEK) and toluene is widely used as solvents in industrial installations. Ketones are used for precipitating solid paraffinic hydrocarbons, adn toluene is used for dissolving the oil part of the feedstock. The basic problems in the practical use of these solvents are considered in [1-3].