Dynocon

How often is everyone changing fluid?

bdewey

I change mine every 40000 miles. I think manual says 36.000 miles I believe.

Shorts

Schedule B has it at 15k. I'm on this one but 15k is too short for my truck. Going to extend a bit.

papaduck

Manual says 15k or 30k depending on the use. I change the front at 30k and the rear at 15k. Hardly ever use the front but the rear gets a workout while towing.

Grit Dog

CHanged out to Amsoil at 20k mi. Just did it again at 100k. Fluid looked pretty good. 15-30k is ridiculous IMO unless you're working the p!ss out of the truck.

LawDawg

how many qts does it take?

Dr.Dizzle

AAM calls for 75w/90 GL-5 differential fluid. The rear 11.5 axle will take 122 oz. or 3.8 quarts and the front 9.25 will take 76 oz. or 2.375 quarts. Therefore,you will need 7 quarts.

LawDawg

Thx Dr.Dizzle.... My truck has 78k on it and I'm pretty sure it's never been changed & I've got five qts of royal purple 75w/90 so I'll do the rear tomorrow and then I'll pick up two more and do the front next weekend

jhenson

I used to haul 26k on a daily basis and I changed both diffs at 100k (for the first time) and it was still just as clear as the day it was put in at the factory. For the price of that synthetic oil, the recommended intervals would break the bank for a guy (like me) that hauls/hauled everyday and really cranked out the miles. I put 225k miles on my truck in less than 2 yrs....do the math!!!!

Dr.Dizzle

Diff lubricants are available at various price points. One standout is Mobil 75w/90 GL-5 , which can be found for 8.99 or so. I could see a product such as Royal Purple at 19.99 a burden on the finances. Keep in mind,however;a large percentage of the wear metals generated by an axle shed off during the first few thousand miles of operation during the axle break in period. Since filtration is not present, getting the wear particles out is beneficial in the long run.

Also, increased metallic particles present in the lubricant increase the oxidation rate of the lubricant and depletes the additive package at a faster rate as it tries to cope. Scheduled changes increase the potential life of the axle as well as increase the working life of the lubricant. If one plans on owning a vehicle for long time, or work it hard, it's certainly worth the investment.

LawDawg

i was given the 7qts when a buddys shop closed up is the ONLY reason i have them... other wise it would have the cheap stuff going in it

Dr.Dizzle

Free is good! Royal Purple is a quality product;however, they are very proud of it.

fatpete

How do I know which front/rear end I have? 9.25? 11.5? What do these mean & where do I find? Thanks for the help & sorry for the noobie question.

Grit Dog

That's what you have. 9.25/11.5 are the ring gear diameters. Think all 3rd Gens are AAM (axle mfr) 9.25" front, 11.5" rear.
Might be on the options sticker in the glovebox or whereever it is, I forget. Or on the window sticker from the dealer.

fatpete

Thanks Grit Dog. I checked the window sticker and it doesn't say the front diff. It does say 11.5 rear, and also says "Anti-Spin Differential Rear Axle." What does this mean? It only cost the original owner $285 extra, so I can't imagine it being too fancy...