i have a 1991 trans am gta. i want to change the rear end diff fluid soon. what should i use? and do i have to use any special additives?

 

Have a limited slip rear end? The safe thing to suggest is to purchase a bottle of GM limited slip additive and three bottles of GL-5 replacement fluid. You can save some money on the oil if you shop around but, I would strongly suggest that you stick with dino oils and not go the other route and blow lots of coin on the synthetics.

 

it leaves two tire marks so i guess its a posi traction but that is the same as limited slip right? where can i get that additive you were talkin about

 

Most autoparts stores have the additive but if not you can get it at the dealership.

Eric

 

ok cool! is it easy to change the rear end fluid? from looking under the car it looked like there was a bar in front of it

 

You'll have to pop the diff cover to change the fluid, so take note if your car is equipped with limited slip (GM's name for the posi). If it is, use GM’s limited slip additive, P/N 1052358. Your dealership will have it in stock. The sway bar will drop when you jack the car up. Check the first pic in the following link (there's also a pic of an Auburn limited slip down a bit):

https://www.thirdgen.org/forums/tran...ing-axles.html

JamesC

 

awsome sounds easy! thanks man. how much gear oil should i use? and what weight would u reccomend?

 

Easy, but messy. You'll need to button up with a gasket or RTV before you refill. I use Mobil 1 LS gear lube, 75-90, with GM additive. I'm unsure what the manual calls for. Wade says three bottles, which sounds right.

JamesC

 

what do you mean button up with a gasket or rtv?

 

You'll need to place a bead of RTV around the diff housing or use a gasket in its place to keep the diff from leaking when you put the cover back on. You'll probably see pieces of the old gasket when you remove the cover (Make sure you scrap it away before you put the new gasket on).

JamesC

 

oh ok i know what you're talking about now lol