He mentioned about noise and gear wear. On mine, the diff bearings were starting to pit, plus the gears were wearing, and the reason I noticed it was it seemed to be making quite a bit of noise (howling) from what sounded like the back end. After I replaced everything brand new (Ford) which was under extended warranty I can't hear any noise what so ever. The thing is if it calls for syn. lube thats what I would like to use. Just wondering if anyone else had heard of that type of problem.