A lubricating oil composition for refrigerating machines contains a base oil and an additive in a form of a naphthalimide compound. A refrigerant used in a refrigerating machine in which the composition is used is unsaturated hydrofluorocarbon (unsaturated HFC) having a GWP of 1000 or less. When the present lubricating oil composition for refrigerating machines is used in refrigerating equipment such as an open-type automobile air-conditioner, an electric automobile air-conditioner, a gas heat pump, other air-conditioning equipment, a refrigerating machine, a vending machine, a showcase, a water-heating system and a refrigerating/heating system, it is possible to detect the leakage of a refrigerant with a long-lasting stability. Therefore, when an unsaturated fron refrigerant with a poor stability is used in the above-listed equipment, the present lubricating oil composition for refrigerating machines is significantly advantageous.

A synergistic mixture comprising from 1 to 99.9% by weight of compounds having structural elements (I) ##STR00001##
in which the free valencies on the oxygen atom and on the nitrogen atom may be combined to form a five-, six- or seven-membered ring and the benzene ring may also bear substituents at one or more of the free positions, and from 0.1 to 99% by weight of sulfur-containing organic compounds with antioxidant action. This synergistic mixture is suitable as a stabilizer for stabilizing inanimate organic material, especially mineral oil products and fuels, against the action of light, oxygen and heat.

A lubricating oil composition for refrigerating machines contains a base oil and an additive in a form of a coumarin compound. When the present lubricating oil composition for refrigerating machines is used in refrigerating equipment such as an open-type automobile air-conditioner, an electric automobile air-conditioner, a gas heat pump, other air-conditioning equipment, a refrigerating machine, a vending machine, a showcase, a water-heating system and a refrigerating/heating system, it is possible to detect the leakage of a refrigerant with a long-lasting stability. Therefore, when an unsaturated chlorofluorocarbon refrigerant with a poor stability is used in the above-listed equipment, the present lubricating oil composition for refrigerating machines is significantly advantageous.

A lubricating oil composition for refrigerating machines contains a base oil and an additive in a form of a naphthalimide compound. A refrigerant used in a refrigerating machine in which the composition is used is unsaturated hydrofluorocarbon (unsaturated HFC) having a GWP of 1000 or less. When the present lubricating oil composition for refrigerating machines is used in refrigerating equipment such as an open-type automobile air-conditioner, an electric automobile air-conditioner, a gas heat pump, other air-conditioning equipment, a refrigerating machine, a vending machine, a showcase, a water-heating system and a refrigerating/heating system, it is possible to detect the leakage of a refrigerant with a long-lasting stability. Therefore, when an unsaturated freon refrigerant with a poor stability is used in the above-listed equipment, the present lubricating oil composition for refrigerating machines is significantly advantageous.

A synergistic mixture comprising from 1 to 99.9% by weight of compounds having structural elements (I) ##STR00001##
in which the free valencies on the oxygen atom and on the nitrogen atom may be combined to form a five-, six- or seven-membered ring and the benzene ring may also bear substituents at one or more of the free positions, and from 0.1 to 99% by weight of sulfur-containing organic compounds with antioxidant action. This synergistic mixture is suitable as a stabilizer for stabilizing inanimate organic material, especially mineral oil products and fuels, against the action of light, oxygen and heat.

A lubricating oil comprises a major amount of a base oil and a minor amount of an additive package, and the additive package comprises at least one friction modifier of formula I: ##STR00001##
where R is a linear or branched, saturated, unsaturated, or partially saturated hydrocarbyl having about 8 to about 22 carbon atoms or R is represented by: ##STR00002##
and R.sub.1 is a linear or branched, saturated, unsaturated, or partially saturated hydrocarbyl having about 8 to about 22 carbon atoms and R.sub.2 is hydrogen or a hydrocarbyl having about 1 to about 2 carbon atoms. Methods of using the lubricating oil to improve thin film and/or boundary layer friction in an engine are also disclosed.

A friction reducing additive is described formed by a mixture that is obtainable by autocatalytic condensation reaction of fatty acids with alkanolamines. The mixture includes an amide, one or more esters of carboxylic acids, and an oxazoline in an amount greater than 7% by weight with respect to the total weight of the mixture, wherein the additive may be used both in lubricants and in fuels.