What is the Oil Recommendation for my Diff?

I have a 1989 GTA 3.27

 

Use a 90w gear oil. Most have the additive for the Limited Slip already in it. If I recall somewhere, there was a bulletin out where it didn't need the additive. I've been using it for years with no problem.

Maybe somebody can chime in about it. It may be personal preference to use or not to use.

 

You can try the 80W90 oil without the bottle of additive and see if it works. If the rear end pops and jerks when turning tight corners then you will need to add a bottle of the GM limited slip oil additive.

 

9-bolt doesn't need additive; its clutches are metal. Not subject to the effects that organic clutch materials are.

Generally, that rear is not real picky about fluid.

I agree that most anything in about a 90 weight oil is fine. Stay away from the heavy stuff like the 75W-140 and such as that. From yer generic parts store 85W-90 in a 5-gallon bucket to synthetic, all of it is fine. My personal preference is Mobil1 75W-90 but there's plenty of others that will work well too.

 

Hi and thanks for the Info:

I bought this for mine. Will it hurt anything if I add the GM additive?

 

Won't hurt anything other than your wallet.

 

Thanks William...