Posted by John G. from NC on January 24, 01 at 11:47:27:
OK, here's one of those -- "Did I screw up" questions. I've got a '99 K2500 with the 3.73 locking rear end. I never did see the fine print at the end of the maintenance section of the owner's manual that said "Replace fluid in locking differentials at first 3,000 miles." (break-in of sorts) OK, so I never did that.
Nevertheless, I discovered my little error when the truck had 16,400 miles, so I had it done at a Chevy dealer then. Better late than never, right?
Reviewing service records the other day, I noticed the dealer service invoice said "Drain and flush differential, replace diff gasket & refill gear lube & posi fluid." I took the dealer invoice to mean that "posi fluid" is the friction modifier fluid used in earlier years. I'm thinking they added friction modifier fluid, not knowing that it was no longer called for in '99 models.
My owner's manual states that you should use GM p/n 1052271 gear oil, with NO additional friction modifier fluid.
Recently, at 42,000 miles, I had the rear end drained and filled again, this time ONLY with GM p/n 1052271 gear oil.
My question --
Did my differential undergo any possible damage between 16,400 miles and 42,000 miles because the friction modifier fluid was probably present? Can't say that I really understand what the stuff is or how it works to modify friction...
Any feedback?
Thanks!