Disclosed are a gear oil composition for automobiles containing at least (A) a base oil, (B) a sulfur-based extreme pressure agent, and (C) a phosphorus-based extreme pressure agent and satisfying specific requirements (i) and (ii), which is excellent in seizing resistance and wear resistance and also in fuel-saving performance, and a lubrication method using the gear oil composition.

Disclosed are a gear oil composition for automobiles containing at least (A) a base oil, (B) a sulfur-based extreme pressure agent, and (C) a phosphorus-based extreme pressure agent and satisfying specific requirements (i) and (ii), which is excellent in seizing resistance and wear resistance and also in fuel-saving performance, and a lubrication method using the gear oil composition.

An aspect of the present invention relates to a lubricant composition containing at least: (A) 50 to 80 mass % of silicone oil represented by formula (1) below, and having a mass-average molecular weight of 900 to 4000, a ratio (C/Si ratio) of carbon to silicon of 3.03 or higher in the structure, and a viscosity index (VI) of 300 or higher; (B) 10 to 49 mass % of hydrocarbon-based lubricant; and (C) 1 to 10 mass % of antioxidant.

An aspect of the present invention relates to a lubricant composition containing at least: (A) 50 to 80 mass % of silicone oil represented by formula (1) below, and having a mass-average molecular weight of 900 to 4000, a ratio (C/Si ratio) of carbon to silicon of 3.03 or higher in the structure, and a viscosity index (VI) of 300 or higher; (B) 10 to 49 mass % of hydrocarbon-based lubricant; and (C) 1 to 10 mass % of antioxidant.

Provided is a lubricating oil composition for a shock absorber, the lubricating oil composition being capable of emitting fluorescence by ultraviolet irradiation while ensuring thermal stability and abrasion resistance. This lubricating oil composition for a shock absorber contains, as components: (A) a base oil; (B) a hydrocarbon compound having a stilbene structure; and (C) a phosphite ester.

Provided is a lubricating oil composition for a shock absorber, the lubricating oil composition being capable of emitting fluorescence by ultraviolet irradiation while ensuring thermal stability and abrasion resistance. This lubricating oil composition for a shock absorber contains, as components: (A) a base oil; (B) a hydrocarbon compound having a stilbene structure; and (C) a phosphite ester.

The present invention provides a method for producing a refrigerating machine oil, comprising blending a hydrocarbyl hydrogen phosphite having an acid value of 100 mgKOH/g or less with a lubricating base oil or an oil composition containing a lubricating base oil, and a refrigerating machine oil obtained by the method.

The present invention provides a method for producing a refrigerating machine oil, comprising blending a hydrocarbyl hydrogen phosphite having an acid value of 100 mgKOH/g or less with a lubricating base oil or an oil composition containing a lubricating base oil, and a refrigerating machine oil obtained by the method.

The present invention provides a refrigerating machine oil containing a lubricating base oil, a dialkyl hydrogen phosphite having two alkyl groups having 1 to 12 carbon atoms in the molecule, and an epoxy compound.

The present invention provides a refrigerating machine oil containing a lubricating base oil, a dialkyl hydrogen phosphite having two alkyl groups having 1 to 12 carbon atoms in the molecule, and an epoxy compound.