I have a 03 silverado electric 4 wheel drive and i'm changing the fluid in the transfer case,rear end and front differencial and needing to know what type fluid to use.Thanks Joe

 

I went through this same ordeal when i got my truck! lol

I used 80-90 Gear oil in the front and rear end, and i think Dexron 3 ATF in the transfer case. You are supposed to use the Blue ACDELCO Automatic transfer case fluid which is about 5 dollars a quart and you need three quarts for the T case. (15 dollars total) Ive got 3K miles on these fluids in my truck and i have not had a single issue, the Tcase and everything runs smooth and clean, and my mechanic told me there is zero damage risk in doing this. I think you are supposed to use 75-90 in the Diffs, but for a truck with high mileage thicker oil makes things last longer and silences the noise. I would encourage you get the blue fluid from your dealer, and do it right, because if you dont know the condition of the Tcase different fluid *may* Swell seals or make something go funky and cause issue.

Sage

 

Use GM Trak ll Blue Oil for the transfer case, 80-90w gear oil for the front axle since its not a locker. The rear may or may not be a locker. If it is you must use a synthetic oil, Valvoline, lucas or any good brand, 80-90w is OK. If its a non locker than any 80-90w gear oil. Look in your glove box for the RPO codes to see if you have a locker rear end. You can get the Trak ll at summit racing or other online venders instead of buying from the stealer