Polyalkylene glycols useful as lubricant additives for hydrocarbon base oils

A lubricant composition comprising:

• a hydrocarbon base oil;
• a polyoxypropylene polymer prepared by polymerizing propylene oxide with an initiator containing a labile hydrogen;
• and
• a polyoxyalkylene polymer prepared by polymerizing an alkylene oxide feed with an initiator containing a labile hydrogen, the alkylene oxide feed comprising from 100 to 25 percent butylene oxide and from 0 to 75 percent propylene oxide, each by weight based on the total weight of the alkylene oxide feed, provided that when the alkylene oxide feed contains greater than 50 weight percent propylene oxide, the initiator is a C8-C20 alkyl alcohol,
• the hydrocarbon base oil, polyoxypropylene polymer and polyoxyalkylene polymer being soluble with one another, with the proviso that the polyoxypropylene polymer is from 10% to 80% of the composition;
• and with the further proviso that if the polyoxyalkylene polymer were fully replaced by the polyoxypropylene polymer, then the hydrocarbon base oil and polyoxypropylene polymer would not be soluble with one another.