Patent ID: 8324140

Claim:
A method of lubricating a refrigerator, the method comprising lubricating the refrigerator with a refrigerator oil composition, comprising a base oil and a carbon dioxide refrigerant, wherein the base oil is polyoxyalkylene glycol and has a kinematic viscosity at 100° C. of from 9.7 to 20.5 mm 2 /sec, a viscosity index of 94 to 218, and a water content of 150 to 250 ppm, wherein the polyoxyalkylene glycol is represented by the following general formula (I): R 1 —[(OR 2 ) m —OR 3 ] n (I) where R 1 represents a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, an acyl group having from 2 to 10 carbon atoms, or an aliphatic hydrocarbon group having from 2 to 6 bonding sites and having from 1 to 10 carbon atoms; R 2 represents an alkylene group having from 2 to 4 carbon atoms; R 3 represents a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, or an acyl group having from 2 to 10 carbon atom; n represents 1; and m represents a number to give a mean value of m×n falling between 6 and 80.