Provided is an engine oil lubricant composition with improved fuel efficiency and engine wear protection. The lubricant composition may include a major amount of an oil basestock from any one or more Group I, Group II, Group III, Group IV or Group V base oils. The resulting engine oil lubricant composition may have a kinematic viscosity at 100° C. of 6 cSt or less, and a corrosion protection of at least 90, as measured according the ASTM D6557 Ball Rust Test. The resulting engine oil lubricant composition may also have a kinematic viscosity at 100° C. of 6 cSt or less, an HTHS (ASTM D4683) of less than or equal to 2.2 cP at 150° C. and a FZG failure load stage of at least 6, as measured by the FZG A10/16.6R/130 test procedure.

The present invention provides a refrigerating machine oil comprising: a base oil; a compound represented by the following formula (1):

##STR00001##

wherein R.sup.1 and R.sup.2 each independently represent a monovalent hydrocarbon group, R.sup.3 represents a divalent hydrocarbon group and R.sup.4 represents a hydrogen atom or a monovalent hydrocarbon group; and an epoxy compound.

A lubricant composition comprises a lubricant and a stabilizer. The stabilizer comprises a first epoxide group and a second functional group selected from the group consisting of (i) a second epoxide group; (ii) an aliphatic carbon-carbon multiple bond conjugated with a second carbon-carbon multiple bond; (iii) an aliphatic carbon-carbon multiple bond conjugated with an electron withdrawing group; and (iv) an aliphatic carbon-carbon multiple bond conjugated with an aromatic group. A heat transfer composition comprises a lubricant composition as described above and a haloalkane, such as an iodoalkane (e.g., trifluoroiodomethane).

A lubricant composition comprises a lubricant and a stabilizer. The stabilizer comprises a first epoxide group and a second functional group selected from the group consisting of (i) a second epoxide group; (ii) an aliphatic carbon-carbon multiple bond conjugated with a second carbon-carbon multiple bond; (iii) an aliphatic carbon-carbon multiple bond conjugated with an electron withdrawing group; and (iv) an aliphatic carbon-carbon multiple bond conjugated with an aromatic group. A heat transfer composition comprises a lubricant composition as described above and a haloalkane, such as an iodoalkane (e.g., trifluoroiodomethane).

Provided is an engine oil lubricant composition with improved fuel efficiency and engine wear protection. The lubricant composition may include a major amount of an oil basestock from any one or more Group I, Group II, Group III, Group IV or Group V base oils. The resulting engine oil lubricant composition may have a kinematic viscosity at 100° C. of 6 cSt or less, and a corrosion protection of at least 90, as measured according the ASTM D6557 Ball Rust Test. The resulting engine oil lubricant composition may also have a kinematic viscosity at 100° C. of 6 cSt or less, an HTHS (ASTM D4683) of less than or equal to 2.2 cP at 150° C. and a FZG failure load stage of at least 6, as measured by the FZG A10/16.6R/130 test procedure.

A lubricant composition comprises a lubricant and a stabilizer. The stabilizer comprises a first epoxide group and a second functional group selected from the group consisting of (i) a second epoxide group; (ii) an aliphatic carbon-carbon multiple bond conjugated with a second carbon-carbon multiple bond; (iii) an aliphatic carbon-carbon multiple bond conjugated with an electron withdrawing group; and (iv) an aliphatic carbon-carbon multiple bond conjugated with an aromatic group. A heat transfer composition comprises a lubricant composition as described above and a haloalkane, such as an iodoalkane (e.g., trifluoroiodomethane).

A lubricant composition comprises a lubricant and a stabilizer. The stabilizer comprises a first epoxide group and a second functional group selected from the group consisting of (i) a second epoxide group; (ii) an aliphatic carbon-carbon multiple bond conjugated with a second carbon-carbon multiple bond; (iii) an aliphatic carbon-carbon multiple bond conjugated with an electron withdrawing group; and (iv) an aliphatic carbon-carbon multiple bond conjugated with an aromatic group. A heat transfer composition comprises a lubricant composition as described above and a haloalkane, such as an iodoalkane (e.g., trifluoroiodomethane).

The present invention provides a refrigerating machine oil comprising: a base oil; a compound represented by the following formula (1): ##STR00001##
wherein R.sup.1 and R.sup.2 each independently represent a monovalent hydrocarbon group, R.sup.3 represents a divalent hydrocarbon group and R.sup.4 represents a hydrogen atom or a monovalent hydrocarbon group; and an epoxy compound.

A refrigeration cycle apparatus including, a compressor, a condenser, a pressure reducer, and an evaporator that evaporates the refrigerant. The refrigerant is a mixed refrigerant which contains refrigerant components of difluoromethane, pentafluoroethane and trifluoroiodomethane and which has a global warming potential and a specific vapor pressure. The compressor is a sealed electric compressor which includes a compression mechanism and a motor to drive this compression mechanism, and which is charged with a refrigerator oil to lubricate a sliding portion, and the refrigerator oil is polyvinyl ether oil, and contains 0.1% by mass to 2.0% by mass of a stabilizer constituted by at least one of an alicyclic epoxy compound and a monoterpene compound, 0.1% by mass to 2.0% by mass of an acid scavenger constituted by an aliphatic epoxy compound, and 0.1% by mass to 2.0% by mass of an extreme pressure agent constituted by tertiary phosphate.

The present invention provides a refrigerating machine oil comprising: a base oil containing an ester of dipentaerythritol with 2-methylbutanoic acid and n-pentanoic acid; and at least one epoxy compound selected from the group consisting of a glycidyl ester compound and a glycidyl ether compound, the refrigerating machine oil being used with a difluoromethane refrigerant.