Abstract: Batch auto-refrigerative dewaxing processes employing at least two batch chilling vessels can be improved by integrating the batch auto-refrigerative dewaxing chilling cycles of the chilling vessels so as to have their cycles of operation overlap and use thermocompressors to recover the energy of the hot, high pressure cycle stream of one vessel by operation on the cooler, low pressure cycle stream of the other vessel to increase the pressure of said low pressure cycle stream. The overlap operation of the multiple batch chillers integrated through the thermocompressor will also permit running the cool, low pressure cycle to a pressure even lower than atmospheric without inleakage of air because of the vacuum effect generated by the hot, higher pressure stream running through the thermocompressor. Autorefrigerative dewaxing employs liquified normally gaseous solvents as the chilling solvents such as C.sub.3 -C.sub.4 alkanes/alkenes e.g. propane, propylene, butane, butylene and mixtures thereof.

Abstract: Hydrocarbon dewaxing using propane or other autorefrigerative dewaxing solvent can be practiced in a centrifuge wherein the centrifugal force generated in the centrifuge produces a pressure gradient permitting dewaxing to be practiced on a continuous basis.

Abstract: Copolymers of dialkyl fumarate and vinyl acetate having Specific Viscosities of at least 2.5 at 2% polymer concentration in xylene at 40.degree. C., and wherein at least 50 wt. % of said alkyl groups are C.sub.20 to C.sub.24, are useful as dewaxing aids, particularly in propane dewaxing.

Abstract: Copolymers of dialkyl fumarate and vinyl acetate having Specific Viscosities of at least 2.5 at 2% polymer concentration in xylene at 40.degree. C., and wherein at least 50 wt. % of said alkyl groups are C.sub.20 to C.sub.24, are useful as dewaxing aids, particularly in propane dewaxing.

Abstract: A solvent dewaxing process is described comprising mixing a waxy hydrocarbon oil, preferably a waxy petroleum oil, most preferably a waxy lube or specialties oil, with dewaxing solvent and a dewaxing aid comprising (A) a dialkylfumarate-vinyl laurate copolymer and (B) a wax-naphthalene condensation copolymer, a dialkyl fumarate-vinyl acetate copolymer or an ethylene vinyl acetate copolymer and chilling the mixture to yield a slurry comprising solid particles of precipitated wax and a solution of dewaxed oil and solvent and separating said solid wax from dewaxed oil solution.