I've got about 400miles on Mobil 1 synthetic with no additive at all. I just read that with stock posi you should run conventional. Can anyone explain why? Also, are people just running GM additive? This is for a stock 10 bolt.

 

That makes 2 of us. I've heard different stories now. I just went with synthetic lube, but I'm not sure whether I need to put the additive in, and I'm not sure how good this will be for my rear end. OTOH, I do have a hankering for a Torsen T2R, so if the old one blows up, I'll have a good excuse.

 

I've been using mobil 1 synthetic with 1 or 2 bottles of the GM additive.. no problems

 

You need the additive. I prefer the non-synth. The posi is deigned to operate best with non-synth. Synth is too slippery.

Rich Krause

 

Thankyou.

 

I bought this car used, and when changing all the fluids I put in Mobil 1 synthetic without the GM additive and it whined around corners. After going back and adding the additive, it quit whining.

 

Thanks guys!

I will put the additive in myself.