Hey guys I want to change my differential fluid,would like to know everything I'll need to tackle it,I.e. what fluid is recommended/additive? What sealant is good to get a good seal?Thank you guys that's pretty much I wanna do,anything else you guys suggest I do while I'm there.

 

any GL5 rated 70-90 wt non synthetic gear oil. if you have a Limited Slip differential use a 4 oz bottle of GM Friction Modifier (aka "additive")

FelPro makes a gasket for the cover for a few $ available at most auto part stores

 

Why non-synthetic?

 

If you have a "open" differential (non limited slip) synthetic is OK...but for a limited slip differential synthetics are not recommended per Eaton & Auburn

The synthetic and the clutch material used in either LS diff don't work well together. A gear only differential synthetics are OK

 

I recently purchased mine from the GM Dealership. These are the original lubes with new updated part numbers.

AC Delco Axle Lube = #89021669 - 23 oz. bottle - Qty 3 (You need 56 oz.)

AC Delco Limited Slip Axle Lube = #88900330 - 4 oz. bottle - Qty 1

More expensive than the auto stores, but it is the recommended stuff by GM.

 

Per the Owner's Manual, anything that meets SAE 80W-90 API GL5 is acceptable. There is nothing magic about GM putting their part # on it.

In the past, I was adamant about the use of non-synthetic fluids in the Eaton and Auburn limited slips. I posted quotes on this site and others, from the manufacturers' websites recommending conventional lubes only. BUT.... my Strange 12-bolt, with the Eaton super-duty clutch type limited slip has had synthetic lube in it for 16 years.

When the unit was shipped to me, Strange forgot the ABS reluctor gear. Sort of a big deal, because it is actually machined into the Eaton carrier, not a pressed-on ring like the stock carrier. Since I had already installed the rear assembly when I discovered there was no reluctor gear, by sticking my finger in the sensor hole, Strange proposed that they ship a new carrier to a shop that we could mutually agree on, and that shop would change out the carrier, with a warranty from Strange on the work. The shop we agreed on used synthetic. I watched him install it. As an **** mechanical engineer, I questioned the guy doing the work, but he told me not to worry. I knew this guy was the best around, and had been building and racing cars for 30 years. Never had a problem. A few years later, the shop that built my stroker changed out the gears to a set of US/Strange Pro-Street 4.11's. The shop, which has my complete faith and respect used synthetic.

Here we are, 16 years later, and never had a problem of any kind with the Eaton/synthetic setup.

 

yeah Fred I too read on both Eaton & Auburn sites regarding the ? "what type of fluid to use" and both said non synthetic with a 4 oz bottle of friction modifier. So like you I always followed that point.

Your 16 year "test" would indicate the synthetic fluid is OK with the clutch pack material. It may be that either manufacturer never tested synthetics, let alone several brands, and only had test/compatibility data on dino fluid which is why they only recommend that type of fluid

I just follow what the manufacturer advises on fluid compatibility.....but obviously YMMV as it has in your case

 

Cool thank you guys a lot for the information,car is at 136xxx miles now, i apologize for not adding signature,also is there any specific place that has the right fluid and additive,like oreilys and auto zone

94 camaro lt1 m6,long tubes headers, stock,

 

Any auto part store will have the gear oil. O'Rielys carries a Friction Modifier made by Lubeguard. I have always just bought a 4 0z bottle of GM or Ford additive at the dealership parts dept.

$ range of the Friction Modifier is around $4-$8 depending on where you get it