Abstract: A lubricating oil composition for agricultural machines, containing: at least one base oil selected from the group consisting of mineral oil-based base oils and synthetic oil-based base oils; and a polyalkyl methacrylate-based viscosity index improver having a weight average molecular weight of from 20,000 to 80,000, in which a kinematic viscosity at 100° C. is from 8.00 mm2/s to 10.00 mm2/s, a kinematic viscosity reduction rate at 100° C. in an ultrasonic shear stability test is 10.0% or less, and a Brookfield viscosity at ?40° C. is 20,000 mPa·s or less.

Abstract: A lubricating oil composition includes at least one base oil selected from the group consisting of a mineral oil-based lubricating oil, a synthetic oil-based lubricating oil, and a mixed oil thereof, zinc dialkyldithiophosphate X represented by Formula (1), and an acid phosphate ester amine salt Y represented by Formula (2), in which a content PX of the X is from 0.06% by mass to 0.08% by mass in terms of phosphorus concentration with respect to a total mass of the lubricating oil composition, and a content PY of the Y is from 0.015% by mass to 0.025% by mass in terms of phosphorus concentration with respect to the total mass of the lubricating oil composition.

Abstract: A lubricating oil composition includes at least one base oil selected from the group consisting of a mineral oil-based lubricating oil, a synthetic oil-based lubricating oil, and a mixed oil thereof, zinc dialkyldithiophosphate X represented by Formula (1), and an acid phosphate ester amine salt Y represented by Formula (2), in which a content PX of the X is from 0.06% by mass to 0.08% by mass in terms of phosphorus concentration with respect to a total mass of the lubricating oil composition, and a content PY of the Y is from 0.015% by mass to 0.025% by mass in terms of phosphorus concentration with respect to the total mass of the lubricating oil composition.

Abstract: A lubricating oil composition including: at least one base oil selected from a mineral oil-based lubricating oil, a synthetic oil-based lubricating oil, or a mixed oil thereof, and zinc dialkyldithiophosphates X consisting of the compounds Z1 to Z3 represented by the formulae (1) to (3) are contained, in which a total content of the zinc dialkyldithiophosphates X is 0.02% by mass or more in terms of phosphorus concentration with respect to the total mass of the oil composition, and the zinc dialkyldithiophosphates X satisfy the formulae (a) to (c). In the formula (1), each of R1 to R4 independently represents a linear or branched primary alkyl group having from 10 to 20 carbon atoms. In the formula (2), each of R5 to R8 independently represents a linear or branched primary alkyl group having from 7 to 9 carbon atoms. In the formula (3), each of R9 to R12 independently represents a linear or branched primary or secondary alkyl group having from 3 to 6 carbon atoms.

Abstract: A lubricating oil composition including: at least one base oil selected from a mineral oil-based lubricating oil, a synthetic oil-based lubricating oil, or a mixed oil thereof, and zinc dialkyldithiophosphates X consisting of the compounds Z1 to Z3 represented by the formulae (1) to (3) are contained, in which a total content of the zinc dialkyldithiophosphates X is 0.02% by mass or more in terms of phosphorus concentration with respect to the total mass of the oil composition, and the zinc dialkyldithiophosphates X satisfy the formulae (a) to (c). In the formula (1), each of R1 to R4 independently represents a linear or branched primary alkyl group having from 10 to 20 carbon atoms. In the formula (2), each of R5 to R8 independently represents a linear or branched primary alkyl group having from 7 to 9 carbon atoms. In the formula (3), each of R9 to R12 independently represents a linear or branched primary or secondary alkyl group having from 3 to 6 carbon atoms.