What gear oil do I get..?? Please help I gotta install them by Thursday!

**ManMuchwano93Z28** · 07-29-2013, 03:02 AM

Hey guys so I got some 3.73 richmonds and a ratech install kit I was wondering what oil do I get and is there any other oil's/ Lubricants I would need..?? And I'm scheduling to install them this Thursday

***popo8*** · 07-29-2013, 04:57 AM

If they are going in a posi or limited slip carrier u will need the posi additive.

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**RamAir95TA** · 07-29-2013, 04:59 AM

2 quarts of synthetic 75w90 plus the GM limited slip additive.

***popo8*** · 07-29-2013, 05:22 AM

Originally Posted by RamAir95TA

...llimited slip additive.

That what i meant

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***meissen*** · 07-29-2013, 05:44 AM

Is the limited slip additive necessary in all cases? I have the T/A girdle and was re-seating the girdle with a fresh ring of sealant to stop the rear from leaking. I put 3 quarts of Castrol Syntech 75w90 gear oil in my rear end about a month ago and never added the additive?

(And that damn thing still wasn't full with 3 quarts!)

**RamAir95TA** · 07-29-2013, 06:02 AM

If you have a limited slip differential then YES you need the additive. It keeps the clutch packs in the posi from chattering when they grab and release during turns.

**Sapper** · 07-29-2013, 07:09 AM

It's pricey but you can get the GM fluid which is already synthetic with the additive in it. Any GM dealer will have it. We use alot of it. p/n 88900401 @ $35/qt. You need 2. to fill from empty.

**SS RRR** · 07-29-2013, 07:33 AM

Screw that. Just get regular gear oil that RamAir suggested and additive.

***popo8*** · 07-29-2013, 08:09 AM

Originally Posted by Sapper

It's pricey but you can get the GM fluid which is already synthetic with the additive in it. Any GM dealer will have it. We use alot of it. p/n 88900401 @ $35/qt. You need 2. to fill from empty.

I tried that with my old 10bolt...still chattered till i hit it with the additive.

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**Sapper** · 07-29-2013, 09:40 AM

Larry, Are you sure it was this p/n and not the regular 75/90, p/n 88862624. That's the older stuff and required the additive. Normally 2 bottles to stop it from chattering.
We get quite a few trucks in here that the customers will change their diff fluid when doing their own maintenance and complain of noise. We'll drain and refill with the 0401 fluid and all better.

Or you can run Amsoil and it stops chatter without an additive and alot cheaper.