Demonic85

I know you've all seen this topic probably a million times, but I searched the forum and couldnt find the answer I needed. I need to change the rear differential fluid. I know that I need 75w90 gear oil, but i'm not sure which brand to use. Also, Where can I find the limited slip additive? I havent found any places that carry it.

mothersworry

I use Mobil 1 Synthetic. You can get the limited slip additive from the dealer. You will ned two bottles of the limited slip additive

Demonic85

How much do you think a dealer would charge for the additive? And if its that big of a pain, how much would they charge to do it, you think?

rocco16

Get the GM gear lube and the GM LS additive. It ain't expensive and you'll know it's the right stuff. I don't have my maintenance records with me at the moment, so I can't tell you what it cost me, but I do know it wasn't enough to make me remember!!!

See your friendly, local Chevrolet dealer for the fluids.....and DO IT YOURSELF!

Larry
code5coupe

xflagz51

If you plan on driving it hard, then use a synthetic 75W-90. The synthetic will stand up to the heat and abuse better than a coventional. But be careful! Most of your high performance sythetic gear oils(like Red Line and even Mobil1)come with friction modifier already blended in. This is a case where too much is not a good thing.

Best of luck,

Adam.

Nico

I even could buy it here in Spain, probably the only thing I could buy for my vette here.
The additive was approx 11 $ and the synthetic was made of gold, 60$ a liter. But that may be way cheaper in the USA.

xflagz51

Fair enough. LOL Synthetic is probably cheaper here in the US. Sorry!

C4CBF

I used Valvoline synthetic 75W-90 last night. Works great. You are going to have to get a 2 way pump and pump the old fluid out of the fill hole. Kind of a PITA, have rags handy

C4STL

I looked on Mobil's web site and they say for their synthetic 75w-90 gear lube ,it already has LS(limited slip) additives in it. Says only need to add LS additive for extreme duty,and is compatible with their lube. I'm changing mine too. Bought that Mobil 1 synthetic and tube of additive at Advanced Auto Parts. Autozone sells additive as well . In blue tube made by K&W , has 7 oz. Less than $5! Also says meets GM specs . The owners manual for my'89 says use 4oz. of additive.

Demonic85

Thanks guys. I checked on the price and Mobil 1 synthetic fluid was like $8 a quart. Thats not too bad at all.

Brian86

How many quarts are needed?

aboatguy

You need to buy two quarts and you will have about half a quart leftover for next time.

Last time this topic turned a little ugly.

According to my FSM the D44s and D36s have the same fluid capacity.