What kind of gear oil do you use with a posi rear end? Is there a special additive as well?

I think you use gear oil (90w i think) and you can buy the additive from GM. Some synthetics have the additive in already i believe as well.

I dont have a Posi, but I am sure there is an additive that you have to add to it. Like kevin mentioned you can pick it up "off the shelf" from either a dealer or UAP, they should have it.

if you dont add the additive your gears will feel like they are binding or sticking a little at slow speeds and when making a turn

Your best bet is to use a full-synthetic multi-viscosity gear oil (i.e. 75W-90) and genuine GM posi additive- available at any GM dealership and it's about $8.00 (or was last time I bought some). The 'pre-treated' i.e. with a posi-additive already in it, gear oils have too much crap in them to cover all the different manufacturers (Ford, GM, Chrysler) posi's.

I changed mine last year and used the Motormaster Synthetic (I think it only comes in one kinda weight) with the GM additive. Are you doing a full fluid change? If you need help let me know...it will only cost ya a beer!

Hey Irocker, you got it! I would like to do it asap because I think I've lost a fair bit of fluid already (the last thing I want to do is replace the gears too!) So it'll have sit in the mean time

Well if you can manage a trip to Brampton with it we can do it this weekend...otherwise just give me a call and we'll figure it out.

I forgot all about gear oil... Thats one thing I know nothing about... I havent checked mine since I bought the ROC...