Grease base oil

Abstract

To provide a grease base oil which has excellent compatibility with nonpolar polymer materials and which exhibits superior water resistance, heat resistance, and low-temperature fluidity.SOLUTION: A grease base oil comprises a polyalkylene glycol-based compound represented by formula (1). R1O-(EO)m-(PO)n-R2 (1). (In formula (1), R1 represents an alkyl group having 1 to 3 carbon atoms, R2 represents a methyl group or hydrogen, EO represents an oxyethylene group, PO represents an oxypropylene group, EO and PO are added randomly, m represents an average added mole number of EO and is a number of 1 to 8, n represents an average added mole number of PO and is a number of 5 to 30, and a mass ratio of EO to PO is EO:PO=10:90 to 20:80).SELECTED DRAWING: None