A fluorine-containing ether compound represented by the following formula. R.sup.1CH.sub.2R.sup.2aCH.sub.2R.sup.3aCH.sub.2R.sup.2bCH.sub.2R.sup.3bCH.sub.2R.sup.2cCH.sub.2R.sup.3cCH.sub.2R.sup.2dCH.sub.2R.sup.4 (R.sup.2a, R.sup.2b, R.sup.2c and R.sup.2d are each a perfluoropolyether chain, R.sup.3a, R.sup.3b, and R.sup.3c are each a divalent linking group having one or more polar groups, at least one of R.sup.3a, R.sup.3b, and R.sup.3c is represented by OCH.sub.2CH(OH)CH.sub.2O, and R.sup.1 and R.sup.4 are each a terminal group having 1 to 50 carbon atoms and one or more polar groups, and may be the same as or different from each other)

A fluorine-containing ether compound represented by the following formula. R.sup.1CH.sub.2R.sup.2[CH.sub.2R.sup.3CH.sub.2R.sup.2].sub.xCH.sub.2R.sup.4 (x is 1 or 2, R.sup.2 is a perfluoropolyether chain, R.sup.3 is represented by Formula (2), and R.sup.1 and R.sup.4 are each a terminal group having 1 to 50 carbon atoms, which has 1 to 4 polar groups, and in Formula (2), a1 and a2 are each 0 to 5, b is 0 or 1, and Y is an acyclic divalent saturated hydrocarbon group having 2 to 8 carbon atoms) ##STR00001##

A fluorine-containing ether compound represented by the following formula. R.sup.1CH.sub.2R.sup.2[CH.sub.2R.sup.3CH.sub.2R.sup.2].sub.xCH.sub.2R.sup.4 (x is 1 or 2, R.sup.2 is a perfluoropolyether chain, R.sup.3 is represented by Formula (2), and R.sup.1 and R.sup.4 are each a terminal group having 1 to 50 carbon atoms, which has 1 to 4 polar groups, and in Formula (2), a1 and a2 are each 0 to 5, b is 0 or 1, and Y is an acyclic divalent saturated hydrocarbon group having 2 to 8 carbon atoms) ##STR00001##

A lubricant composition, including 20 to 99.5 wt. %, based on a total weight of the lubricant composition, of a base oil, the base oil having a solubility for ionic liquid methyltrioctylammonium-bis(fluorosulfonyl)imide of at least 3 wt. % at a room temperature of 20 C. The base oil contains a base stock A in a proportion of at least 50 wt. %, based on a total weight of the base oil, the base stock A having a solubility for the ionic liquid methyltrioctylammonium-bis(fluorosulfonyl)imide of at least 3 wt. % at a room temperature of 20 C. The lubricant composition further includes 0.5 to 80% wt. %, based on the total weight of the lubricant composition, of an ionic liquid whose anion is bis(fluorosulfonyl)imide.

A lubricant composition, including 20 to 99.5 wt. %, based on a total weight of the lubricant composition, of a base oil, the base oil having a solubility for ionic liquid methyltrioctylammonium-bis(fluorosulfonyl)imide of at least 3 wt. % at a room temperature of 20 C. The base oil contains a base stock A in a proportion of at least 50 wt. %, based on a total weight of the base oil, the base stock A having a solubility for the ionic liquid methyltrioctylammonium-bis(fluorosulfonyl)imide of at least 3 wt. % at a room temperature of 20 C. The lubricant composition further includes 0.5 to 80% wt. %, based on the total weight of the lubricant composition, of an ionic liquid whose anion is bis(fluorosulfonyl)imide.