Whether the additive is needed in the rear diff can be discussed by all of us but that effects the locker or limited slip and not the pinion bearing. That is why I asked if the pinion seal was replaced on the initial go round before the noise came about. Not retensioning the pinion nut, if pinion seal was replaced, is a known problem when doing that. That additive did not cause pinion bearing failure, if in fact that is the problem. I always use what the manual says to use, PERIOD. I do not guess at it at all. The vehicle left the factory with the correct fluid. Use that fluid. I use AC Delco fluids when doing this work. If they did not do a seal, then it is just plain bad luck.
Just finished reading the entire internet about whether or not to use the friction modifier and the answer is NO.
The pinion seal was not replaced during the first fluid Change 2 weeks ago before the noise started.
They just unbolted the cover, cleaned and replaced it and filled it back up.
I checked the invoice and there is no mention of any additives added. (The first time)
I noticed the noise right after I picked it up and just excused because of the thinner gear oil I provided and or the spare tire being dropped and being able to hear more of the diff noises..
But it got louder.
This evening when I picked the truck up, I questioned the friction modifier listed on the invoice and he said they added it because it was a "LS".
Now I'm 6 hours into reading all there is about the G80 locking differential.
Yawn..
