A working fluid composition for a refrigerating machine, containing: a refrigerant containing trifluoroiodometbane; and a refrigerating machine oil containing a polyol ester and a hindered phenol compound, wherein a content of the hindered phenol compound is 0.6 to 10% by mass based on a total amount of the refrigerating machine oil.

A working fluid composition for a refrigerating machine, containing: a refrigerant containing trifluoroiodometbane; and a refrigerating machine oil containing a polyol ester and a hindered phenol compound, wherein a content of the hindered phenol compound is 0.6 to 10% by mass based on a total amount of the refrigerating machine oil.

A lubricating oil composition may be capable of satisfactorily exhibiting sludge prevention properties and wear resistance evaluated by scoring resistance and seizure resistance over a long period of time. Such a lubricating oil composition may contain: a base oil (A); a hindered phenol-based antioxidant (B); one or more imide compounds (C) selected from the group consisting of a monoimide compound (C1) and a bisimide compound (C2); and an extreme pressure agent (D), in which the hindered phenol-based antioxidant (B) is 2,6-di-tert-butylphenol, the monoimide compound (C1) is one or more selected from the group consisting of an alkenyl succinic monoimide compound and an alkyl succinic monoimide compound, and the bisimide compound (C2) is one or more selected from the group consisting of an alkenyl succinic bisimide compound and an alkyl succinic bisimide compound.

A lubricating oil composition may be capable of satisfactorily exhibiting sludge prevention properties and wear resistance evaluated by scoring resistance and seizure resistance over a long period of time. Such a lubricating oil composition may contain: a base oil (A); a hindered phenol-based antioxidant (B); one or more imide compounds (C) selected from the group consisting of a monoimide compound (C1) and a bisimide compound (C2); and an extreme pressure agent (D), in which the hindered phenol-based antioxidant (B) is 2,6-di-tert-butylphenol, the monoimide compound (C1) is one or more selected from the group consisting of an alkenyl succinic monoimide compound and an alkyl succinic monoimide compound, and the bisimide compound (C2) is one or more selected from the group consisting of an alkenyl succinic bisimide compound and an alkyl succinic bisimide compound.

The invention is directed to a method for reducing low speed pre-ignition events in a spark-ignited direct injection internal combustion engine by supplying to the sump a lubricant composition which contains an oil of lubricating viscosity and an ashless dispersant. The ashless dispersant may be selected from succinimide compounds prepared from aliphatic or aromatic amines.

The invention is directed to a method for reducing low speed pre-ignition events in a spark-ignited direct injection internal combustion engine by supplying to the sump a lubricant composition which contains an oil of lubricating viscosity and an ashless dispersant. The ashless dispersant may be selected from succinimide compounds prepared from aliphatic or aromatic amines.

Disclosed herein is a process for preparing an isomeric mixture comprising a major amount of a para-branched mono-alkyl-substituted hydroxyaromatic compound. The process involves the steps of: (a) providing an isomeric mixture comprising a major amount of a para-di(alkyl-substituted)aromatic compound; wherein a first alkyl substituent is a C.sub.3 to C.sub.8 alkyl moiety and a second alkyl substituent is a C.sub.4+n to C.sub.8+n branched alkyl moiety, wherein n is 0 to 42 and further wherein the second alkyl substituent is at least one carbon atom greater than the first alkyl substituent; (b) subjecting the isomeric mixture comprising a major amount of a para-di(alkyl-substituted)aromatic compound to oxidation conditions in the presence of an oxygen-containing source, thereby converting the first alkyl substituent which is a C.sub.3 to C.sub.8 alkyl moiety to a hydroperoxide-containing substituted moiety to produce an isomeric mixture comprising a major amount of a para-branched alkyl-substituted, hydroperoxide-containing substituted aromatic compound; and (c) converting the hydroperoxide-containing substituted moiety to a hydroxyl moiety thereby providing an isomeric mixture comprising a major amount of a para-branched mono-alkyl-substituted hydroxyaromatic compound.

Disclosed herein is a process for preparing an isomeric mixture comprising a major amount of a para-branched mono-alkyl-substituted hydroxyaromatic compound. The process involves the steps of: (a) providing an isomeric mixture comprising a major amount of a para-di(alkyl-substituted)aromatic compound; wherein a first alkyl substituent is a C.sub.3 to C.sub.8 alkyl moiety and a second alkyl substituent is a C.sub.4+n to C.sub.8+n branched alkyl moiety, wherein n is 0 to 42 and further wherein the second alkyl substituent is at least one carbon atom greater than the first alkyl substituent; (b) subjecting the isomeric mixture comprising a major amount of a para-di(alkyl-substituted)aromatic compound to oxidation conditions in the presence of an oxygen-containing source, thereby converting the first alkyl substituent which is a C.sub.3 to C.sub.8 alkyl moiety to a hydroperoxide-containing substituted moiety to produce an isomeric mixture comprising a major amount of a para-branched alkyl-substituted, hydroperoxide-containing substituted aromatic compound; and (c) converting the hydroperoxide-containing substituted moiety to a hydroxyl moiety thereby providing an isomeric mixture comprising a major amount of a para-branched mono-alkyl-substituted hydroxyaromatic compound.

The present invention is able to provide a lubricating oil composition for compression refrigerating machine having excellent thermal/chemical stability even when used for a compression refrigerating machine using a saturated fluorinated hydrocarbon refrigerant having a low carbon number and a low global warming potential, by using a refrigerant containing a saturated fluorinated hydrocarbon having from 1 to 3 carbon atoms, which uses, as a base oil, an oxygen-containing organic compound composed of at least one member selected from a polyoxyalkylene glycol, a polyvinyl ether, a copolymer of a poly(oxy)alkylene glycol and a polyvinyl ether, a copolymer of a poly(oxy)alkylene glycol monoether and a polyvinyl ether, and a polyol ester, each having a hydroxyl value of not more than 15 mgKOH/g.

The present invention is able to provide a lubricating oil composition for compression refrigerating machine having excellent thermal/chemical stability even when used for a compression refrigerating machine using a saturated fluorinated hydrocarbon refrigerant having a low carbon number and a low global warming potential, by using a refrigerant containing a saturated fluorinated hydrocarbon having from 1 to 3 carbon atoms, which uses, as a base oil, an oxygen-containing organic compound composed of at least one member selected from a polyoxyalkylene glycol, a polyvinyl ether, a copolymer of a poly(oxy)alkylene glycol and a polyvinyl ether, a copolymer of a poly(oxy)alkylene glycol monoether and a polyvinyl ether, and a polyol ester, each having a hydroxyl value of not more than 15 mgKOH/g.