Extended drain, thermally stable, gear oil formulations

1. A gear oil composition comprising the following components:

Component A: a base oil having a kinematic viscosity at 100° C. of about 4 to about 32 cSt;

Component B: a di-t-butyl tri-sulfide, di-t-butyl tetra-sulfide, and di-t-butyl penta-sulfide mixture having a sulfur activity of greater than about 125 mg in the Copper Corrosion Test;

Component C: a dihydrocarbyl dithiophosphate ester or salt; and

Component D: a dihydrocarbyl (mono)thiophosphate amine salt.

2. The gear oil of claim 1 , wherein Component B comprises less than about 3.5 percent by weight of the gear oil.

3. A gear oil composition comprising the following components:

Component A: a base oil having a kinematic viscosity at 100° C. of about 4 to about 32 cSt;

Component B: a di-t-butyl tri-sulfide, di-t-butyl tetra-sulfide, and di-t-butyl penta-sulfide mixture having a sulfur activity of greater than about 125 mg in the Copper Corrosion Test;

Component C: the product of the mixture of dicyclopentadiene and dialkyldithiophosphoric acid, wherein the weight percentage of Component C is about 0.1 to about 6.0 percent of the oil; and

Component D: a dihydrocarbyl (mono)thiophosphate amine salt.

4. The gear oil of claim 1 , wherein Component D is essentially free of phosphites.

5. The gear oil of claim 1 , wherein Component D comprises the product of the mixture of dibutylhydrogen phosphite, sulfur and at least one amine.

6. The gear oil of claim 4 , wherein the weight percentage of Component D is about 0.01 to about 1.0 percent of the oil.

7. The gear oil of claim 1 further comprising at least one of:

a copper corrosion inhibitor, a rust inhibitor and an antifoam agent.

8. The gear oil of claim 1 further comprising:

a boronated ashless dispersant.

9. The gear oil of claim 8 wherein said dispersant is a succinimide.

10. The gear oil of claim 8 wherein said dispersant is a Mannich base dispersant.