How much posi additive for fluid change?

[SkyGod]

I have a couple 10 bolt Posi's I'm refilling.
How many bottles of additive do I need and what is the recommended gear oil...80w90?
I'd like to go synthetic if possible.
Thanks.

 

[Doog]

Mobil1 75w90LS or Valvoline synthetic 75w90 should have the additive in it. If you get some chatter add 2 ounces of LS additive and drive it 20 miles then do some cornering and see if it still chatters. If so add another 2 ounces until the chatter stops. Too much LS additive is as bad as not enough so be easy with the additive. My guess with the Mobil1 you won't need any.

 

[Highline9]

What kind of posi unit?

 

[SkyGod]

72 and 77 GM Eaton units.
Thanks.

 

[Warstud]

Check Autozone for the Mobil 75w90LS...a few weeks ago they had it on sale for $6.99 qt.

 

[CharBaby]

I just bought 3 qts of Mobil 1 75w90LS at AAP for $10.99/qt. All 3 stores in my driving area(AAP, AZ, PB's) all are the same price right now!

I wish I had cought the $6.99 special at AZ

That would have been like getting one for free!

 

[dailydriver]

Originally Posted By: SkyGod
72 and 77 GM Eaton units.
Thanks.


Those use steel clutchpacks, correct??

Are they rebuilt with new springs/internals, or just cleaned up and re-installed?

 

[SkyGod]

Unknown condition.
Both vehicle projects were bought recently.
I'm in the process of replacing all the fluids.
I removed the old rusty cover,didn't find much in the way of metal shavings.
The cover has been off before...there was rtv sealer all over the gasket surface.
Replaced the cover with a new one,with drain plug.

 

[Donald]

Look up on the Amsoil website for the specific vehicles and diff. They tell you exactly how many ounces and in many cases its a dealer item they suggest, not an Amsoil product. Also not all diffs are filled to the bottom of the fill hole. Some are to be filled 1/2" below. They tell you that also. Even if you never buy an Amsoil product, check it out, they have a lot of good vehicle specific info (including capacity).