A mixed composition including a refrigerant including at least one unsaturated fluorinated hydrocarbon compound selected from the compound having a formula C.sub.xF.sub.yH.sub.z, x is an integer of 2 to 6, y is an integer of 1 to 11, z is an integer of 1 to 11, and the compound has at least one unsaturated carbon-carbon bond, and a refrigerator oil including a base oil (A); a phosphorus-based extreme pressure agent (B); a decomposition inhibitor (C) that inhibits the decomposition of the unsaturated fluorinated hydrocarbon in the presence of an iron; and an antioxidant (D), wherein (C) controls the amount of fluorine in the refrigerator oil composition at 30 ppm by mass or less after mixing the refrigerator oil with R1234yf at a mass ratio of 1:1, and subjecting the mixture to an autoclave test at 175° C. for 336 hours with a metal catalyst including iron, copper, and aluminum.

A lubricating oil composition may include a base oil (A), succinimide (B) which has not been modified with boron, succinimide (C) modified with boron, a metallic detergent (D), and an antioxidant (E), wherein the ratio of the content of boron atoms derived from ingredient (C) to the content of nitrogen atoms derived from ingredients (B) and (C), B/N, is 0.30 or less by mass, the lubricating oil composition satisfying requirement (I) and/or requirement (II). Requirement (I): Ingredient (D) includes a metallic detergent (D1) having a base value less than 100 mgKOH/g. Requirement (II): Ingredient (E) includes an amine-based antioxidant (E1), the content of ingredient (E1) being 1.00 mass % or less.

A lubricating oil composition containing a base oil (A), a comb-shaped polymer (B), and an olefin-based copolymer (C), wherein a content of the component (B) is more than 0.80 mass % based on the total amount of the lubricating oil composition, a weight average molecular weight of the component (C) is 500,000 or more, and the lubricating oil composition has a viscosity index of 200 or more and a kinematic viscosity at 100° C. of 9.3 to 11.0 mm.sup.2/s.

A hydrocarbon fluid is disclosed that has a pour point of at most −30° C., as measured by ASTM D5950, and that comprises at least 99 wt % of naphthenes and paraffins, based on the total weight of the hydrocarbon fluid, wherein the weight ratio of naphthenes to paraffins is at least 1, as measured by GC-MS, and wherein the paraffins consist essentially of isoparaffins, as determined by GC-FID. In addition, preferred uses of said hydrocarbon fluid are disclosed.

A mixed powder for powder metallurgy comprises: an iron-based powder; and a lubricant, wherein the lubricant consists of a low-melting-point lubricant having a melting point of 86° C. or less and a high-melting-point lubricant having a melting point of more than 86° C., the low-melting-point lubricant has at least one of an amide group, an ester group, an amino group, and a carboxyl group, a ratio R1 of the low-melting-point lubricant to whole of the lubricant is 5 mass % or more and less than 90 mass %, a ratio R2 of a mass of a free lubricant to a mass of a binding lubricant is 0 or more and 15 or less, and an amount R3 of the low-melting-point lubricant contained as the free lubricant is less than 0.10 parts by mass with respect to 100 parts by mass of the iron-based powder.

Provided are a lubricant composition for shock absorbers, a lubricant additive, and a method of adjusting friction characteristics of a lubricant composition for shock absorbers, each capable of satisfying both the operational stability and ride comfort. The lubricant composition for shock absorbers contains a base oil and a friction adjusting agent, the friction adjusting agent contains pentaerythritol esters, and the pentaerythritol esters contain a pentaerythritol tetraester and a pentaerythritol ester other than the pentaerythritol tetraester.

Provided is an engine oil lubricant composition with improved fuel efficiency. The engine oil lubricant composition may include: a polyalpha olefin base oil component an amount of about 50 wt % to about 90 wt % based on a total weight of the engine oil lubricant composition, wherein the polyalpha olefin base oil component is a Group IV base oil and has a Noack volatility of about 12.5% to about 15%; a Group II base oil component in an amount of about 0.1 wt % to about 50 wt % based on the total weight of the engine oil lubricant composition. The engine oil lubricant composition may have (i) a kinematic viscosity at 100° C. of about 10 cSt or less, (ii) a high temperature high shear viscosity at 150° C. of about 2.2 cP or less, and (iii) a Noack volatility of about 20% or less.

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.

Provided is a lubricating oil composition to be used in an internal combustion engine having a sliding mechanism including a piston ring and a liner, the lubricating oil composition including: a base oil; (A) a poly(meth)acrylate; and (B) an organic molybdenum compound, in which: (A) the poly(meth)acrylate contains a polymer (A1) including a repeating unit derived from a (meth)acrylate represented by the following formula (1) and having a mass-average molecular weight of from 1,000 to 500,000; and a content of (B) the organic molybdenum compound in a total amount of the composition is from 0.01 mass % to 0.2 mass % in terms of a molybdenum atom: wherein R.sup.1 represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a hydrocarbon group having 1 to 60 carbon atoms, or a functional group-containing hydrocarbon group having 1 to 60 carbon atoms.

The lubricating oil composition according to the present invention is one including a base oil, (A) a substituted hydroxy aromatic carboxylic acid ester derivative represented by at least one of the general formula (I) and the general formula (II), and (B) a heterocyclic compound represented by the general formula (III) or (IV) blended therein, wherein a phosphorus content is 0.06 mass % or less on the basis of a total amount of the composition, and a sulfated ash content is 1.2 mass % or less on the basis of a total amount of the composition. The lubricating oil composition is capable of maintaining high-temperature detergency and acid neutralizing properties, even when amounts of a phosphorus component-containing additive and a metallic detergent are reduced.