diff fluid questions?

[Wildstreak]

I just popped the front and rear end diff to change fluids(and see what was up with the front) and found I have a posi rear. since Im planning on changing fluids I was wondering if I should go with a synthetic like royal purple or what?

[lilred67]

whatever gear oil you choose i would suggest adding a bottle of GM differential additive to it. without it your posi may not work properly.
i run mobil 1 85/90 fs in my posi's...

[capev86]

i have RP in my saginaw 3 on the tree and plan to run it in the Ho52 rear when i get the third member swapped for the 4.10 unit i have ready to go. we all know the trans and rear end get worked hard and are often neglected.....good place to spend some extra folding green for the sake of dependability.

[hotrod 80]

I just changed the ring and pinion and added a fresh rebuilt posi . I am starting with royal purple .

[Longhorn Man]

synthetic is the way to go

[unclewatts]

In 1989 I put synthetic 80wt. gear oil (Amsoil) in my posi rear end. 100,000 miles later, a few months ago I had the oil changed. The guy at the garage who changed it swore the gears were brand new. Go synthetic. BTW, I used GM limited slip additive. That's the best.

[63chevyll]

I like Synthetic, but not a MUST for a used rear end,

Reg old 75w90 or 80w90 or 75w140 will do fine with any posi additive for a used posi unit

[Longhorn Man]

conventional oil will do... but if the funds are there, you are better off with better oil.

[Wildstreak]

thanks guys I never knew you had to ad an additive, good thing I asked you all. tomorrow Ill get some royal purple and some additive and some gaskets as well

[Wildstreak]

is there any special additive for the front or is just reg 80/90 do?

[cdowns]

if you use royal purple theres no need for the posi additive

[vegaschevy]

You should ask GM or Dana what thy think of Amsoil, or any other component manufacture. NONE recommend it as a good synthetic lubricant

[mosesburb]

GM recommends:

Gear oil: 1052271
and
Additive: 1052358

You can use what you want, but that is what Generous Motors recommends.

[vegaschevy]

Originally Posted by mosesburb

GM recommends:

Gear oil: 1052271
and
Additive: 1052358

You can use what you want, but that is what Generous Motors recommends.

GM approves many types of oils, just like with the Allison transmission in the diesels. They however have approved hundreds of oils for the allison but NO AMSOIL!!!! In fact your warranty will be void by GM if another unapproved oil is used in a failed allison tranny.
The hype with amsoil blows my mind.If it is so great, why does no manufacture recommend it? hmmmm especially one offering a no questions asked warranty.....

[chaosdsr]

CDowns is right Royal Purple has the additive in it so if you go that route dont buy the posi additive. Oh and on the Amsoil thing in auto transmissions its ****, it soaks into clutches and can cause slipping which is why you will not see it recommended for any allison or many autos for that matter. Amsoil is horrible for almost any auto trans app and even worse in a streetbike application!

[vegaschevy]

Originally Posted by chaosdsr

CDowns is right Royal Purple has the additive in it so if you go that route dont buy the posi additive. Oh and on the Amsoil thing in auto transmissions its ****, it soaks into clutches and can cause slipping which is why you will not see it recommended for any allison or many autos for that matter. Amsoil is horrible for almost any auto trans app and even worse in a streetbike application!

It has nothing to do with the clutches but with the oil itself. No one endorses or approves this oil except themselves.

[Wildstreak]

Originally Posted by cdowns

if you use royal purple theres no need for the posi additive

I bought the royal purple but it says limited slip they didnt have one for posi. I bought the additive as well, should I need it or is there an actual posi fluid>?

[LONGHAIR]

Originally Posted by Wildstreak

I bought the royal purple but it says limited slip they didnt have one for posi. I bought the additive as well, should I need it or is there an actual posi fluid>?

"Posi-traction" is just GMs word for limited slip, like a brand name. It's the same thing. And no, you don't need the additive, it's already there.

[Wildstreak]

sahweet, do you guys use a diff cover gasket and some sealant or just some good form gasket stuff? dont wanna leak out all the good stuff lol

[lilred67]

many gear oil list "for limited slips" on the bottle, but that doesn't mean your posi will like it. before i added the gm ls additive to mine i used some from the local parts store and valvoline 80/90. posi chattered. drained, added gm ls, & mobil 1, no problems.

[Wildstreak]

is there any tips on a sealant and gasket to use that prevent leaks?

[Wildstreak]

weird went to the parts store today and they dont have a gasket for the dana 44 front at all. It was the same store that was clueless with the motor mounts tho, so I shouldnt have expected any better. did they make on or was he just being lazy?

[LONGHAIR]

Yes, there is a gasket for Dana 44, front or rear doesn't matter.

[Wildstreak]

thats why he couldnt find it, because he most probably was looking for a dana 44 front and all the had was the rear.

[hayhauler71]

Originally Posted by Wildstreak

sahweet, do you guys use a diff cover gasket and some sealant or just some good form gasket stuff? dont wanna leak out all the good stuff lol

Some syn gear oils will attack some form-a-gasket read the tube or just use the gasket.