A lubricating oil composition for refrigerating machines contains a base oil and an additive in a form of a hydrocarbon compound having a biphenyl structure or a stilbene structure. 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 lubricant composition is provided which comprises a base oil and hydroxytyrosol and/or esters thereof. Also provided is a lubricant composition in which the esters have a solubility in the base oil at 25° C. of at least 0.1 g/l. Further provided is a lubricant composition in which the esters are at least partly carboxylic acid esters comprising esters of hydroxytyrosol and C.sub.2-10 carboxylic acids.

Provided is a lubricating oil composition for air compressors containing a polyalkylene glycol-containing base oil (A) and a rust-preventive agent (B), wherein the content of the polyalkylene glycol is 65.0% by mass or more based on the total amount of the composition. The lubricating oil composition is excellent in oxidation stability and also in rust prevention and storage stability. Also provided are an air compressor lubricating method and an air compressor using the lubricating oil composition.

Provided is a lubricating oil composition for air compressors containing a polyalkylene glycol-containing base oil (A) and a rust-preventive agent (B), wherein the content of the polyalkylene glycol is 65.0% by mass or more based on the total amount of the composition. The lubricating oil composition is excellent in oxidation stability and also in rust prevention and storage stability. Also provided are an air compressor lubricating method and an air compressor using the lubricating oil composition.

A composition comprising water, a glycol, and a polyalkylene glycol which has a biodegradability of at least 60% as determined using OECD 301F wherein the composition has a kinematic viscosity of at least 25 mm.sup.2/sec at 40° C. is useful as a rheology modifier, particularly in subsea applications. In some instances, the composition comprises 10 to 65 weight % water, 20 to 60 weight % of a glycol selected from ethylene glycol, diethylene glycol, triethylene glycol and tetra ethylene glycol, 10 to 40 weight % of a polyalkylene glycol, and 0 to 10% of additives based on total weight of the composition wherein the polyalkylene glycol has a—molecular weight of no more than 4000 g/mol and is characterized in that it is an oxyethylene/oxypropylene block copolymer having a weight percent of oxyethylene of at least 20% based on total weight of the copolymer.

A composition comprising water, a glycol, and a polyalkylene glycol which has a biodegradability of at least 60% as determined using OECD 301F wherein the composition has a kinematic viscosity of at least 25 mm.sup.2/sec at 40° C. is useful as a rheology modifier, particularly in subsea applications. In some instances, the composition comprises 10 to 65 weight % water, 20 to 60 weight % of a glycol selected from ethylene glycol, diethylene glycol, triethylene glycol and tetra ethylene glycol, 10 to 40 weight % of a polyalkylene glycol, and 0 to 10% of additives based on total weight of the composition wherein the polyalkylene glycol has a—molecular weight of no more than 4000 g/mol and is characterized in that it is an oxyethylene/oxypropylene block copolymer having a weight percent of oxyethylene of at least 20% based on total weight of the copolymer.

The invention addresses a problem of providing a lubricating oil composition for refrigerators excellent in thermal stability for a refrigerant that contains difluoromethane (R32), trifluoroiodomethane (CF.sub.3I) and at least one compound (α) selected from saturated fluorinated hydrocarbon compounds (HFC) except difluoromethane (R32). The lubricating oil composition for refrigerators is used for a refrigerant containing difluoromethane (R32), trifluoroiodomethane (CF.sub.3I) and at least one compound (α) selected from saturated fluorinated hydrocarbon compounds (HFC) except difluoromethane (R32), and contains at least one kind of base oil selected from polyoxyalkylene glycols, polyvinyl ethers, copolymers of a poly(oxy)alkylene glycol or a monoether thereof and a polyvinyl ether and polyol esters, in which the hydroxyl value of the base oil is 15 mgKOH/g or less.

Provided is a lubricating oil composition comprising a base oil (A) containing a polyalkylene glycol (A1) and a polyol ester (A2), a phosphorus-based rust inhibitor (B), and an antioxidant (C) containing an amine-based antioxidant (C1). The lubricating oil composition exhibits a strong effect for suppressing sludge sedimentation even when used for an extended period of time in a high-temperature environment, and has excellent demulsibility and rust preventive properties, and therefore, can be suitably used in turbomachinery, compressors, hydraulic equipment, and machine tools.

Provided is a lubricating oil composition comprising a base oil (A) containing a polyalkylene glycol (A1) and a polyol ester (A2), a phosphorus-based rust inhibitor (B), and an antioxidant (C) containing an amine-based antioxidant (C1). The lubricating oil composition exhibits a strong effect for suppressing sludge sedimentation even when used for an extended period of time in a high-temperature environment, and has excellent demulsibility and rust preventive properties, and therefore, can be suitably used in turbomachinery, compressors, hydraulic equipment, and machine tools.

The present invention relates to a method of processing a workpiece comprising contacting a tool and a workpiece to effect a change in the shape of the workpiece, and applying a metalworking fluid to a surface area where the tool and the workpiece are in contact, where the metalworking fluid contains a propoxylate of the formula R—O—(C.sub.3H.sub.6O).sub.n—H, where R is a branched C.sub.6 to C.sub.20 alkyl and n is from 3 to 30. The invention further relates to the metalworking fluid, and to a use of the propoxylate as additive in metalworking fluids.