Lubricating oil composition

1. A lubricating oil composition, comprising:

a base oil (A);

a neutral phosphorus compound (B), which is a trisubstituted aromatic phosphate, trisubstituted aliphatic phosphate, or mixture of two or more of any of these;

an acidic phosphorus compound (C);

a sulfur compound (D); and

a metal salt (E), which is a calcium sulfonate,

wherein the neutral phosphorus compound (B), in terms of phosphorus atoms, is present in a range of from 100 to 1500 ppm by mass, based on the total lubricating oil composition mass,

wherein the acidic phosphorus compound (C), in terms of phosphorus atoms, is present in a range of from 10 to 180 ppm by mass, based on total lubricating oil composition mass,

wherein the acidic phosphorus compound (C) comprises a compound (C1) of formula (c-1), a compound (C2) of formula (c-2), and/or an amine salt (C3) of the compound (C1) or (C2):

R 1 and R 2 in formulas (c-1) and (c-2) independently being a hydrocarbon group comprising 6 to 30 carbon atoms, and m and n independently being 1 or 2, wherein the sulfur compound (D), in terms of sulfur atoms, is present in a range of from 200 to 1000 ppm by mass, based on the total lubricating oil composition mass, wherein the sulfur compound (D) comprises a compound (D1) of fonnula (d-1):

R a and R b independently being a hydrocarbon group, and X1 and X2 independently being an integer in a range of from 1 to 3, and

wherein the metal salt (E), in terms of calcium atoms, is present in a range of from 30 to 180 ppm by mass, based on the total lubricating oil composition mass.

2. The composition of claim 1 wherein the neutral phosphorus compound (B), in terms of phosphorus atoms, is present in a range of from 200 to 1000 ppm by mass, based on the total lubricating oil composition mass.

3. The composition of claim 1 , comprising the compound (Cl) of formula (c 1).

4. The composition of claim 1 , wherein the sulfur compound (D) is present in a range of from 300 to 750 ppm.

5. The composition of claim 1 , wherein the metal salt (E) comprises an overbased metal salt (E1) having a base number of 100 mg KOH/g or more.

6. The composition of claim 1 , wherein a (D)/(E) content ratio of the sulfur compound (D), in terms of sulfur atoms, to the metal salt (E), in terms of metal atoms, is in a range of from 3.0 to 20.0, in terms of mass ratio.

7. The composition of claim 1 , having a kinetic viscosity at 40° C. in a range of from 6.0 to 18.0 mm 2 /s.

8. The composition of claim 1 , having a volume resistivity, measured at a measurement temperature of 80° C. and an applied voltage of 250 V, in accordance with JIS C2101, of 5.0×10 7 Ωm or more.

9. The composition of claim 1 , wherein when a shell four-ball abrasion test is performed using the lubricating oil composition at a rotational speed of 1800 rpm, a test temperature of 80° C., a load of 392 N, and a test time of 30 minutes, in accordance with ASTM D4172, a wear scar size of a test ball is 0.70 mm or less.

10. The composition of claim 1 , wherein, when an ISOT test using the lubricating oil composition with a copper piece used as a catalyst is performed at a test temperature of 165.5° C. and a test time of 144 hours, in accordance with JIS K2514, an amount of copper eluted of degraded oil after the test is less than 30 ppm by mass.

11. A method for producing the composition of claim 1 , the method comprising:

blending a base oil (A) with a neutral phosphorus compound (B), an acidic phosphorus compound (C), a sulfur compound (D), and a metal salt (E) comprising a metal sulfonate, a metal salicylate, and/or a metal phenate.

12. A machine, comprising:

the composition of claim 1 .

13. The machine of claim 12 , wherein the machine is a hydraulic system, a stationary transmission, an automotive transmission, or a cooling system configured for a motor and/or a battery.

14. A method of lubricating a machine, the method comprising:

contacting the composition of claim 1 with a hydraulic system, a stationary transmission, an automotive transmission, or a cooling system configured for a motor and/or a battery.

15. The composition of claim 1 , comprising the compound (C2) of formula (c-2).

16. The composition of claim 1 , comprising the amine salt (C3) of the compound (C1) or (C2).

17. The composition of claim 1 , wherein the neutral phosphorus compound (B), in terms of phosphorus atoms, is present in a range of from 200 to 800 ppm by mass, based on the total lubricating oil composition mass.

18. The composition of claim 1 , wherein the neutral phosphorus compound (B) is tricresyl phosphate, triphenyl phosphate, trixylenyl phosphate, dicresyl monophenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, tributoxy phosphate, diphenyhnonotridecyl phosphate, or a mixture thereof.