I am having trouble tracking down my oil leaks. I thought originally it was the rear main, but could it be the input shaft leaking on the tranny (5-sp manual)? I only think this because the oil is always BLACK (even like 5 min after an oil change), and the engine oil level doesen't seem to drop that much. In addition, when I got it the gear lube was low. What are the odds that it is either?

 

The amount of labor to fix either is the same, so pull the gearbox and do both.

 

Is the input shaft seal similar to the rear main in design?