New here, searched some for latest board preferences for type, wgt and brand of gear oil for differentials and transfer cases.

Any favorites? Will use a Miti-Vac if needed; and gear oil change tips?

Thanks!

 

Differentials are both SAE 80W90 GL5. The front differential has a drain and a fill plug. Rear differential requires removing the cover to drain it, and a new gasket.

Transfer case: 3 buttons on the dash switch uses DexronVI. 4 buttons on the dash switch uses Auto-TrakII ONLY. It is available only at a GM dealer, ~$9 per quart, you'll need just under 2 quarts.

 

just did my rear diff, make sure you get the fill plug off BEFORE you remove the cover. Just a heads up. I ended up drilling a hole in the cover to fill mine. i made the mistake of draining before attempting to remove fill plug

 

why do you have to remove the fill plug before the cover? just curious

 

You remove the fill plug first so that you do not risk draining the diff without a means of filling it back up. Otherwise, if the plug refuses to come out and you have already pulled the cover, you will not have an easy time of filling it back up.

 

Quick question, is it necessary to use RTV along with a new gasket when servicing the rear diff? I recently attempted to change the fluid and cover on my truck and in the process noticed that there was RTV residue when I took the cover off. I am fairly certain that it has not been serviced during the life of the vehicle (2003). I say "attempted" because I ordered the wrong cover/gasket so I ended up having to use RTV and put the old cover back on as a temporary measure until I can get the correct cover. The service manual doesn't mention anything other than using a new gasket.

 

I got away with using only the felpro paper gasket. I found it a pain is the a** to slide the cover behind the sway bar without smearing the RTV. I had a paper gasket on for 3 years and no leaks. Just make sure you clean both mounting surfaces well

 

Thanks

 

The Sam's Garage' guys-- Sam and Sam-- always recommend using only the GM synthetic products for the diff and transfer case. Yes, they are expensive so why? They say the low capacity of the transfer case makes it critical that you use only the best syn. oil. Sam Sr. has owned several Chevy 4WD trucks and presently has a 4WD Silverado diesel he uses for towing. It is the old 'pay now or pay later' situation.

 

Wilco