Differential fluid change

How hard and what do I need to get to change the Differential fluid. First time doing this so any advice will do.

thanks

Our moderator has you covered. :)

http://www.bfranker.badz28.com/fbody/lubeoil.htm

Its actually really easy but is a little messy.

You will need 2 quarts of gear oil and the little bottle of additive since the Z28 has a limited slip rear end. Just go to any auto parts store and they should have it. While you are there, get a new gasket for the differential.

A large catch pan, basic set of sockets w/ratchet, putty knife (scrape off old gasket), RTV gasket maker and a torque wrench (not necessary, just don't over tighten the bolts....12-15ft-lbs is all they need) A hand pump will come in handy also for putting new oil back in Diff.

1. Remove bolts with catch pan under diff.
2. Remove cover. Sometime it sticks and will need to pried off. Don't put gouges in the metal though. Try a block of wood and a hammer.
3. Completely Remove old gasket from cover and Diff.
4. Wipe out all old oil and inspect gears for damage.
5. Put a thing layer of RTV on cover and then place gasket on cover
6. Put cover on the Diff. and tighten the bolts in a criss-cross pattern. Tighten to 12 ft-lbs
7. Remove fill plug. Just use a ratchet with nothing on it. Be sure to clean out all the junk inside the hole so you don't round it off.
8. Put in additive bottle and then gear oil until it starts to run out the fill hole.
9. Put fill plug back in and tighten. (I like to add a little RTV to the threads to ensure leak free plug)
10. Go ask girl friend to smell your hands. :) That old gear lube will stink.

For the next couple of days, check the diff. for leaking but I doubt you will have any problems.
Repeat process every 15k miles.

I think I covered everything. Someone else jump in here and add something if need be.


EDIT: Or you could just follow the link above. I just wasted 10 min of my work day.......oh well its still better than working. :D

If you want to save a little work you can use a pump to draw the fluid out so you don't have to take off the cover. Can't do an inspection though.

Two things to add to Joe's instructions:
Synthetic gear lube is not recommended for stock differentials
Add 1 bottle of GM limited slip additive, available from your Chevy dealer for about $7.

Yeah, one thing to do is to take it to a quick lube place and they have the pumps to suck that crap out and normally do it real cheap if you bring your own fluid and additive. I wouldnt trust their limited slip additive as it is universal.

Which one is better.... Sucking out the fluid or removing the diff cover to drain the fluid

Originally posted by ping0317
Which one is better.... Sucking out the fluid or removing the diff cover to drain the fluid

If you are confident there is no nothing wrong with the diff., just suck out the fluid. I prefer to remove the cover just ensure everything looks ok and there isn't any metal shavings in the bottom. You also get a chance to almost completely wipe out all the old fluid.

Why do you say synthetic is not reccommended. I just bought some synthetic to put in mine this weekend because i read on here that it was better. :confused:

Bill

Synthetic is not recommended for stock (auburn type) differentials. Use regular gear lube and GM limited slip additive.

Originally posted by All4Chevy
Why do you say synthetic is not reccommended. I just bought some synthetic to put in mine this weekend because i read on here that it was better. :confused:

Bill


I just changed the fluid in my rear and followed this sites procedures, http://www.bfranker.badz28.com/fbody/lubeoil.htm . My 02 Z28's owner's manual recomends using 75W-90 Synthetic Axle Lubricant (I'm using Mobil One) and GM's Limited-Slip Axle Lubricant Additive. Is the use of Synthetic gear oil only recomened for certain years? All4Chevy, I would check your owners manual and follow it's recomendation's for which type of gear oil to use.

Also, per the above web site, I tightened the differential cover to 22 ft lbs. Was that too much?