As I was changing the oil in the rear differential, there was a tag that says Positraction differential lubricant only, is there a difference in lubricants. I was going to use 85W-90W, is that ok or should I look for a lubricants specifically for positraction?:confused:

As I was changing the oil in the rear differential, there was a tag that says Positraction differential lubricant only, is there a difference in lubricants. I was going to use 85W-90W, is that ok or should I look for a lubricants specifically for positraction?:confused:

Use the 85W-90W as you planned.then use some posi additive.It's a little small bottle 6oz or so.......

you will find it at almost any parts house.....

Get the GM posi-trac additive (2 bottles) and you'll be good.

Or you can use Amsoil synthetic gear lubes, they have the additive built into it already plus it will run cooler for you as well. :)

Thanks team for the info. :beers:

Or you can use Amsoil synthetic gear lubes, they have the additive built into it already plus it will run cooler for you as well. :)

Do you sell Amsoil?

Anyone know off hand how many quarts does a typical 12 bolt rear end take?

Anyone know off hand how many quarts does a typical 12 bolt rear end take?

About 2 qt. is what I used. I also use Royal Purple it has the additive in it also.

2 quarts of oil and one bottle of GM or Ford additive. Don't use the additive that you get at the auto parts store unless it's GM or Ford. Use only one bottle of additive unless you have an Auburn, then use 2 bottles.

What exactly does this bottle of posi additive do?.....Is it an anti foaming agent to prevent the gear lube from foaming?

Redline 75/90 has additive in it and they also have the additive separate.

What exactly does this bottle of posi additive do?.....Is it an anti foaming agent to prevent the gear lube from foaming?
Modifies the lubricant so the clutches slip better going around a corner. No chattering.

Yea, it makes the clutches slip easier.This kind of goes against the purpose of the clutches in the first place. That is why you should only add as much additive as you need. Too much additive makes the posi less effective.

Myself and BigGearHead both have Amsoil available for you, through ordering direct from Amsoil if you want.
PM either of us :)

In my 69 10 Bolts, I used GM oil (80W90, P/N 89021671) with one 4oz bottle of GM Limitted Slip Axle Lubricant Additive (P/N 1052358).

If your running a Ford 9 inch stay away from synthetics, regular 80w90 takes the heat out better. Add your bottle of addative to that. Synthetics dont adhear well to the gears, but they work ok in ten bolts and twelve bolts due to the pinion location. Any questions call Doug Demoss at Quick Performance 515 232 0126.

What about "Lucas"? Will that work without the additive........?

Russell I have to politely disagree. 100% synthetics will cling better to metal surfaces than a pertro. Thats why most NASCAR and NHRA folks use syns. The syn will always run cooler, always. Pike's Peak climber Bobby Unser did a ton of research in his car years ago and the results made everyone else switch over too.
Im afraid you have heard old wives tales about syns.

I put Lucas in mine with no additive but have not ran it yet.

Has anyone else used Lucas?

What about "Lucas"? Will that work without the additive........?