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May 30, 2009 | 01:39 PM

VNVETT

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Racer

Joined: Aug 2000

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From: Augusta, Georgia, USA

Rear end

When replacing break in lube for the rear end using a product such as Royal Purple Synthetic that already has the diff additives do you still have to put in the GM friction modifers????

May 31, 2009 | 03:21 AM

LS WON

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Joined: Dec 2002

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From: San Francisco CA

Quote:

Originally Posted by VNVETT

When replacing break in lube for the rear end using a product such as Royal Purple Synthetic that already has the diff additives do you still have to put in the GM friction modifers????

I know Redline has the addictive already in it and I have no problems using that in my other car.
Amsoil does also but with the Amsoil you can add their slip lock so I have heard on here and people have had good results with the Amsoil and adding a tube 4 ounces of slip lock.
The new GM fluid Dexron L? gear oil recommends that you do not add any type of friction modifer to their fluid.
I have not heard much on the Royal Purple isn't it the new kid on the block as far as synthetics go?

May 31, 2009 | 04:48 PM

calemasters

Le Mans Master

Joined: Jan 2005

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From: Thousand Oaks California

Quote:

Originally Posted by VNVETT

When replacing break in lube for the rear end using a product such as Royal Purple Synthetic that already has the diff additives do you still have to put in the GM friction modifers????

No.

The factory differential does not have break-in oil that requires replacement after X miles. When it is time to replace the oil in the differential, I recomment the GM Dexron LS 75w-90. If do you choose to use the GM Dexron LS 75w-90 gear oil, do not add any additives.

May 31, 2009 | 04:55 PM

burtonbl103

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From: Boston MA

St. Jude Donor '06-'07-'08,'12-'13

nope just use te royal purple !

May 31, 2009 | 05:44 PM

VNVETT

Thread Starter

Racer

Joined: Aug 2000

Posts: 410

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From: Augusta, Georgia, USA

Thanks guys, What I meant was I just put in a stage 2 RPM diff and they told me after 500 miles to put the 75/90 in and I bought the Royal Purple and want to know if I still needed to put in the additives from GM. I think I have my answer. Just put the Royal Purple in .

May 31, 2009 | 07:24 PM

LS WON

Team Owner

Joined: Dec 2002

Posts: 32,074

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From: San Francisco CA

Quote:

Originally Posted by burtonbl103

nope just use te royal purple !

No Redline or Amsoil

May 31, 2009 | 07:49 PM

C66 Racing

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From: King George VA

Quote:

Originally Posted by VNVETT

When replacing break in lube for the rear end using a product such as Royal Purple Synthetic that already has the diff additives do you still have to put in the GM friction modifers????

For the C5, I'd say no, but for the C6 I'm not sure. In my 02 Z06 and my 06 CTS-V, I use the AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 without extra additive and neither diff chatters. But with the C6 diff, it seems to need one extra bottle of friction modifier. Given that parallel, I'd assume, but don't know that the RP would as well. Easiest way to tell is to put it in without extra additive and drive it. If the diff chatters, add a bottle of additive.