Abstract: Disclosed is a method of treating a used hydrocarbon lubricant of ISO Viscosity Grade 46 or higher comprising oxidation products that adversely affect lubricant performance. The hydrocarbon lubricant has a Group II hydrocarbon oil or Group III hydrocarbon oil, optionally one or more lubricant additives, and an amount of varnish. The hydrocarbon lubricant is free of zinc-containing additives. The method comprises adding to the used hydrocarbon lubricant from about 2 percent by weight to about 20 percent by weight of a polyhydroxy polypropylene oxide homopolymer that has a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g as measured according to ASTM D4274.

Abstract: Disclosed is a method of treating a used hydrocarbon lubricant of ISO Viscosity Grade 46 or higher comprising oxidation products that adversely affect lubricant performance. The hydrocarbon lubricant has a Group II hydrocarbon oil or Group III hydrocarbon oil, optionally one or more lubricant additives, and an amount of varnish. The hydrocarbon lubricant is free of zinc-containing additives. The method comprises adding to the used hydrocarbon lubricant from about 2 percent by weight to about 20 percent by weight of a polyhydroxy polypropylene oxide homopolymer that has a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g as measured according to ASTM D4274.

Abstract: Disclosed are methods in which an aliphatic polyether selected from polyalkylene oxides with monomer units having 3 to about 10 carbon atoms and polyvinyl ethers with ether groups having 2 to about 8 carbon atoms is added to a hydrocarbon lubricant; such methods in which the hydrocarbon lubricant comprises oxidation products that are dissolved by the addition of the polyether or polyvinyl ether; hydrocarbon lubricants containing a polyether selected from polyalkylene oxides with monomer units having 3 to about 10 carbon atoms and polyvinyl ethers with ether groups having 2 to about 8 carbon atoms; methods of lubricating machines with these lubricants; lubrication systems including these hydrocarbon lubricants; and machines including these lubrication systems.

Abstract: Disclosed are methods in which an aliphatic polyether selected from polyalkylene oxides with monomer units having 3 to about 10 carbon atoms and polyvinyl ethers with ether groups having 2 to about 8 carbon atoms is added to a hydrocarbon lubricant; such methods in which the hydrocarbon lubricant comprises oxidation products that are dissolved by the addition of the polyether or polyvinyl ether; hydrocarbon lubricants containing a polyether selected from polyalkylene oxides with monomer units having 3 to about 10 carbon atoms and polyvinyl ethers with ether groups having 2 to about 8 carbon atoms; methods of lubricating machines with these lubricants; lubrication systems including these hydrocarbon lubricants; and machines including these lubrication systems.