Disclosed is a lubricating oil composition comprising an oil of lubricating viscosity and an oil soluble synergistic mixture of antioxidants, said mixture comprising: a) a hindered amine antioxidant according to formula (I)

##STR00001## wherein each R.sup.1 is independently selected from a substituted or unsubstituted, branched or linear, C.sub.1-C.sub.20 hydrocarbyl group; R.sup.2 is selected from the group consisting of a hydrogen atom or a, substituted or unsubstituted, branched or linear, C.sub.1-C.sub.20 hydrocarbyl group; each R.sup.3 is independently selected from the group consisting of a hydrogen atom or a, substituted or unsubstituted, branched or linear, C.sub.1-C.sub.20 hydrocarbyl group; each R.sup.4 is independently selected from the group consisting of a hydrogen atom or a, substituted or unsubstituted, branched or linear, C.sub.1-C.sub.20 hydrocarbyl group; n is an integer from 1 to 4; and m is an integer from 1 to 5; and b) a molybdenum succinimide complex.

To provide a composition for a heat cycle system, which comprises a working fluid for heat cycle which has a low global warming potential and high stability, and which can replace R410A, and a heat cycle system employing the composition.

A composition for a heat cycle system, which comprises a working fluid for heat cycle containing 1,2-difluoroethylene, and a stabilizer for preventing deterioration of the working fluid for heat cycle, such as an oxidation resistance-improving agent, a heat resistance-improving agent or a metal deactivator, and a heat cycle system employing the composition for a heat cycle system.

A composition that includes one or more compounds represented by the formula

(R.sub.1).sub.a(X)(R.sub.2).sub.b

wherein R.sub.1 and R.sub.2 are the same or different and are the residue of an alkyl group having from about 4 to about 40 carbon atoms, X is the residue of at least one polycyclic, heteroatom-containing, hydrocarbon compound, a is a value from 1 to about 8, and b is a value from 0 to about 8. The composition has a viscosity (Kv.sub.100) from about 2 to about 300 at 100 C. as determined by ASTM D-445, and a viscosity index (VI) from about 100 to about 300 as determined by ASTM D-2270. The disclosure also relates to a process for producing the composition, a lubricating oil base stock and lubricating oil containing the composition, and a method for improving oxidative stability of a lubricating oil by using as the lubricating oil a formulated oil containing the composition.

The invention relates to a compound, to a rubber mixture containing the compound, to a vehicle tire comprising the rubber mixture in at least one component, to a process for producing the compound and to the use of the compound as an aging stabilizer and/or antioxidant and/or antiozonant and/or dye. The compound according to the invention has the formula I). ##STR00001##