Abstract: The lubricating base oil of the invention is characterized by satisfying at least one of the following conditions (a) or (b). (a) A saturated compound content of 95% by mass or greater, and a proportion of 0.1-10% by mass of cyclic saturated compounds among the saturated compounds. (b) The condition represented by the following formula (1). 1.435?n20?0.002×kv100?1.450??(1) wherein n20 represents the refractive index of the lubricating base oil at 20° C., and kv100 represents the kinematic viscosity (mm2/s) of the lubricating base oil at 100° C.

Abstract: The lubricating base oil of the invention is characterized by having an urea adduct value of not greater than 4% by mass and a viscosity index of 100 or greater. The process for production of a lubricating base oil according to the invention is characterized by comprising a step of hydrocracking/hydroisomerization of a stock oil containing normal paraffins, until the obtained treatment product has an urea adduct value of not greater than 4% by mass and a viscosity index of 100 or greater. A lubricating oil composition according to the invention is characterized by comprising the lubricating base oil of the invention.

Abstract: A base oil for hydraulic oil suitably used for hydraulic systems having filters of which micropore diameter is 50 ?m or less is disclosed. The disclosure also provides a hydraulic oil composition using the above base oil, especially a hydraulic oil composition suitably used for such as tractors, transmissions, and common systems thereof having the hydraulic systems. The base oil has mineral oil, and the mineral oil is defined by kinematic viscosity at 100° C.: 1.5˜6 mm2/s, pour-point: ?10° C. or less, viscosity index: 100 or more, % CP: 70 or more, % CA: 2 or less, and aniline point: 106° C. or more, and the mineral base oil is treated by catalytic dewaxing process and/or contains tertiary carbon atoms at a ratio of 7.4% or more to the total carbon atoms.

Abstract: A viscosity index improver of the present invention contains a star polymer obtained by a reaction of divinylbenzene with alkyl methacrylate containing stearyl methacrylate, the star polymer having a core part and an arm part, wherein the core part is derived from the divinylbenzene and the arm part is a polymer chain of the alkyl methacrylate. A lubricant oil additive and a lubricant oil composition of the present invention contain the above viscosity index improver.

Abstract: The shock absorber fluid according to the invention is characterized by comprising a lubricating base oil that has a urea adduct value of not greater than 4% by mass and a viscosity index of 100 or greater. The shock absorber fluid according to the invention can exhibit a high level of all properties including viscosity-temperature characteristic, shear stability and antifoaming property.

Abstract: The present invention provides a lubricating base oil comprising saturated components of 90% by mass or greater, wherein the proportion of cyclic saturated components among the saturated components is not greater than 40% by mass, and by having a viscosity index of 110 or higher and an iodine value of not greater than 2.5. The lubricating base oil of the invention exhibits excellent viscosity-temperature characteristics and heat and oxidation stability while also allowing additives to exhibit a higher level of function when additives are included. The lubricating base oil of the invention is suitable for use in various lubricating oil fields, and is especially useful for reducing energy loss and achieving energy savings in devices in which the lubricating base oil is applied.

Abstract: The lubricating base oil of the invention has a kinematic viscosity at 40° C. of 7 mm2/s or greater and less than 15 mm2/s, a viscosity index of 120 or greater, a urea adduct value of not greater than 4% by mass, a BF viscosity at ?35° C. of not greater than 10,000 mP·s, a flash point of 200° C. or higher and a NOACK evaporation loss of not greater than 50% by mass. The method for producing a lubricating base oil of the invention comprises a step of hydrocracking/hydroisomerizing a feedstock oil containing normal paraffins so as to obtain a treated product having an urea adduct value of not greater than 4% by mass, a kinematic viscosity at 40° C. of 7 mm2/s or greater and less than 15 mm2/s, a viscosity index of 120 or greater, a BF viscosity at ?35° C. of not greater than 10,000 mP·s, a flash point of 200° C. or higher and a NOACK evaporation loss of not greater than 50% by mass. The lubricating oil composition of the invention comprises the lubricating base oil of the invention.

Abstract: The lubricating base oil of the invention has a urea adduct value of not greater than 4% by mass, a kinematic viscosity at 40° C. of 25-50 mm2/s, a viscosity index of 140 or greater, a CCS viscosity at ?35° C. of not greater than 15,000 mPa·s and a flash point of 250° C. or higher. The method for producing a lubricating base oil of the invention comprises a step of hydrocracking/hydroisomerizing a feedstock oil containing normal paraffins so as to obtain a treated product having an urea adduct value of not greater than 4% by mass, a kinematic viscosity at 40° C. of 25-50 mm2/s, a viscosity index of 140 or greater, a CCS viscosity at ?35° C. of not greater than 15,000 mPa·s and a flash point of 250° C. or higher. The lubricating oil composition of the invention comprises the lubricating base oil of the invention.

Abstract: A base oil for hydraulic oil suitably used for hydraulic systems having filters of which micropore diameter is 50 ?m or less is disclosed. The disclosure also provides a hydraulic oil composition using the above base oil, especially a hydraulic oil composition suitably used for such as tractors, transmissions, and common systems thereof having the hydraulic systems. The base oil has mineral oil, and the mineral oil is defined by kinematic viscosity at 100° C.: 1.5˜6 mm2/s, pour-point: ?10° C. or less, viscosity index: 100 or more, % CP: 70 or more, % CA: 2 or less, and aniline point: 106° C. or more, and the mineral base oil is treated by catalytic dewaxing process and/or contains tertiary carbon atoms at a ratio of 7.4% or more to the total carbon atoms.

Abstract: The lubricating base oil of the invention satisfies at least one of conditions (a) or (b) below. The lubricating oil composition for an internal combustion engine according to the invention comprises the lubricating base oil of the invention, an ashless antioxidant containing essentially no sulfur as a constituent element, and at least one compound selected from among ashless antioxidants containing sulfur as a constituent element and organic molybdenum compounds. Also, a lubricating oil composition for a power train device according to the invention comprises the lubricating base oil of the invention, a poly(meth)acrylate-based viscosity index improver and a phosphorus-containing compound. (a) The saturated component content is 90% by mass or greater, and the proportion of cyclic saturated components among the saturated components is 10-40% by mass. (b) The condition represented by the following formula (1) is satisfied. 1.440?n20?0.002×kv100?1.453??(1) [wherein n20 represents the 20° C.

Abstract: The lubricating base oil of the invention has a kinematic viscosity at 40° C. of 7 mm2/s or greater and less than 15 mm2/s, a viscosity index of 120 or greater, a urea adduct value of not greater than 4% by mass, a BF viscosity at ?35° C. of not greater than 10,000 mP·s, a flash point of 200° C. or higher and a NOACK evaporation loss of not greater than 50% by mass. The method for producing a lubricating base oil of the invention comprises a step of hydrocracking/hydroisomerizing a feedstock oil containing normal paraffins so as to obtain a treated product having an urea adduct value of not greater than 4% by mass, a kinematic viscosity at 40° C. of 7 mm2/s or greater and less than 15 mm2/s, a viscosity index of 120 or greater, a BF viscosity at ?35° C. of not greater than 10,000 mP·s, a flash point of 200° C. or higher and a NOACK evaporation loss of not greater than 50% by mass. The lubricating oil composition of the invention comprises the lubricating base oil of the invention.

Abstract: The lubricating base oil of the invention has a urea adduct value of not greater than 4% by mass, a kinematic viscosity at 40° C. of 25-50 mm2/s, a viscosity index of 140 or greater, a CCS viscosity at ?35° C. of not greater than 15,000 mPa·s and a flash point of 250° C. or higher. The method for producing a lubricating base oil of the invention comprises a step of hydrocracking/hydroisomerizing a feedstock oil containing normal paraffins so as to obtain a treated product having an urea adduct value of not greater than 4% by mass, a kinematic viscosity at 40° C. of 25-50 mm2/s, a viscosity index of 140 or greater, a CCS viscosity at ?35° C. of not greater than 15,000 mPa·s and a flash point of 250° C. or higher. The lubricating oil composition of the invention comprises the lubricating base oil of the invention.

Abstract: The invention provides a lubricating base oil with a saturated component content of 90% by mass or greater, a proportion of cyclic saturated components of no greater than 40% by mass of the saturated components, a viscosity index of 110 or greater, an aniline point of 106 or greater and an ?-methylene proportion of 14-20% of the total constituent carbons, as well as a lubricating oil composition comprising the lubricating base oil.

Abstract: Hydraulic oil compositions for shock absorbers comprises a lubricating base oil and at least one type of silicone oil selected from the group consisting of silicone oils with a kinematic viscosity at 25° C. of 10,000 to 350,000 mm2/s and fluorine-modified silicone oils with a kinematic viscosity at 25° C. of less than 10,000 mm2/s. The compositions may further comprise a viscosity index improver. The compositions can enhance the damping force and initial damping properties of a shock absorber and thus improve the ride comfort of an automobile equipped with such a shock absorber.

Abstract: The object of the present invention is to provide a base oil for hydraulic oil suitably used for hydraulic systems having filters of which micropore diameter is 50 ?m or less, which is capable to improve the decrease of flow in a hydraulic pump at low temperature like ?30° C. or less and capable to normally operate the hydraulic systems. The invention also provides a hydraulic oil composition using the above base oil, especially a hydraulic oil composition suitably used for such as tractors, transmissions, and common systems thereof having the hydraulic systems. In order to achieve the object, provided is a base oil for hydraulic oil comprising mineral oil, wherein the mineral oil is defined by kinematic viscosity at 100° C.: 1.5˜6 mm2/s, pour-point: ?10° C. or less, viscosity index: 100 or more, % CP: 70 or more, % CA: 2 or less, and aniline point: 106° C. or more; and wherein, the mineral base oil is treated by catalytic dewaxing process and/or contains tertiary carbon atoms at a ratio of 7.

Abstract: The shock absorber fluid according to the invention is characterized by comprising a lubricating base oil that has a urea adduct value of not greater than 4% by mass and a viscosity index of 100 or greater. The shock absorber fluid according to the invention can exhibit a high level of all properties including viscosity-temperature characteristic, shear stability and antifoaming property.

Abstract: The lubricating base oil of the invention is characterized by having an urea adduct value of not greater than 4% by mass and a viscosity index of 100 or greater. The process for production of a lubricating base oil according to the invention is characterized by comprising a step of hydrocracking/hydroisomerization of a stock oil containing normal paraffins, until the obtained treatment product has an urea adduct value of not greater than 4% by mass and a viscosity index of 100 or greater. A lubricating oil composition according to the invention is characterized by comprising the lubricating base oil of the invention.

Abstract: The present invention provides a lubricating base oil comprising saturated components of 90% by mass or greater, wherein the proportion of cyclic saturated components among the saturated components is not greater than 40% by mass, and by having a viscosity index of 110 or higher and an iodine value of not greater than 2.5. The lubricating base oil of the invention exhibits excellent viscosity-temperature characteristics and heat and oxidation stability while also allowing additives to exhibit a higher level of function when additives are included. The lubricating base oil of the invention is suitable for use in various lubricating oil fields, and is especially useful for reducing energy loss and achieving energy savings in devices in which the lubricating base oil is applied.

Abstract: The lubricating base oil of the invention is characterized by satisfying at least one of the following conditions (a) or (b). (a) A saturated compound content of 95% by mass or greater, and a proportion of 0.1-10% by mass of cyclic saturated compounds among the saturated compounds. (b) The condition represented by the following formula (1). 1.435?n20?0.002×kv100 ?1.450??(1) wherein n20 represents the refractive index of the lubricating base oil at 20° C., and kv100 represents the kinematic viscosity (mm2/s) of the lubricating base oil at 100° C.

Abstract: The lubricating base oil of the invention satisfies at least one of conditions (a) or (b) below. The lubricating oil composition for an internal combustion engine according to the invention comprises the lubricating base oil of the invention, an ashless antioxidant containing essentially no sulfur as a constituent element, and at least one compound selected from among ashless antioxidants containing sulfur as a constituent element and organic molybdenum compounds. Also, a lubricating oil composition for a power train device according to the invention comprises the lubricating base oil of the invention, a poly(meth)acrylate-based viscosity index improver and a phosphorus-containing compound. (a) The saturated component content is 90% by mass or greater, and the proportion of cyclic saturated components among the saturated components is 10-40% by mass. (b) The condition represented by the following formula (1) is satisfied. 1.440?n20?0.002×kv100?1.453 (1) [wherein n20 represents the 20° C.