Ok, so last week my wife spun out on a snow storm and bent my r/r axle on my 1999 GMC Yukon SLT 4X4. I'm replacing the axle this weekend, what kind of fluid does the rear diff take? And do I have to use an additive? Its a locking rear differential, any help is greatley appreciated.......thanks.
What diff fluid do I use?
- Thread starter Nes881
- Start date
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NOFORDS
New Member
I use castrol synthetic 80w-90 gear oil. Some people use other fluids. Some recommend ATF but I tow alot and like something that sticks to your ribs so i go with a heavier weighted oil.
GOOD LUCK. I say that cuz I was in the same situation bout a month ago- needing to know what diff fluid to use, and the suggestions are endless. I searched here and elsewhere on the internet and found so many "opinions" and not one single definite answer. I even called a couple GM dealerships in the area and found conflicting info between them. I ended up having to change out my locked up G80 diff and went with a Detroit True-Trac. It doesnt have any type of clutches so I used Royal Purple synthetic. Sorry I cant give you a definite answer, as I never found one myself. Good luck with your search!
NOFORDS
New Member
use a good diff oil. Use Royal purple, Castrol or Mobil 1 synthetic. There are several things that I don't think anyone should skimp on when it comes to vehicles and one is fluids!
Jimweis
New Member
A quick heads up on OEM diff fluid, before I decided to change my diff all together, I went to the dealership and got their stuff. (3) 23 oz. bottles off diff fluid and friction modifier additive= $48. REGULAR MINERAL OIL-NOT SYNTHETIC. Overpriced BS that was returned the next day.
NOFORDS
New Member
In this case, almost everything gm produces can be improved upon. I suggest you do not use GM issued stuff. Buy a name brand product like one already listed. Your diff will thank you!
GM low rent oil will work, but...
GM low rent oil will work, but...
