[chiphead]

I really don't know. It's some sort of posi rear that was set up by a PO likely 30 years ago when the car was restored. It's either the original LeMans rear that was rebuilt or a transplant from a GTO. I was going to pull the diff cover off and post a picture and have you guys tell me what was in it.

[Greg Reid]

After driving mine a bit without the additive l definitely noticed a little jerkiness at very low speed and tracking in a turn such as turing into a parking space. I put the additive in and it smoothed right out.
I've only had two limited slip Pontiac rears, so my experience is limited to that but they both acted the same way, before and after the additive.

[jhein]

Originally Posted by Greg Reid

After driving mine a bit without the additive l definitely noticed a little jerkiness at very low speed and tracking in a turn such as turing into a parking space. I put the additive in and it smoothed right out.
I've only had two limited slip Pontiac rears, so my experience is limited to that but they both acted the same way, before and after the additive.

Same here. I had lots of clutch binding right after my rebuild. Changed the oil with the GM additive and voila, smooth as silk.

[geeteeohguy]

Originally Posted by Formulabruce

Toss in the 85-90 weight oil. If you REALLY want to add something, add a couple ounces of "Motorkote" to really protect the gears and bearings.
AUBURN style "posi " doesn't need any posi anti chatter lube as its 2 metal cones , no friction material like a Eaton unit.

This is incorrect. The early Pontiac Safe-T-Track limited slips were all cone type and ALL require limited slip additive. Says so on the tag on the diff, and in the factory manuals. Without the additive, you will get chatter and rough operation.