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#4449788 - 07/04/17 07:37 PM GM 2012 AAM 8.6" rear diff need additive?
SquirrelMan Offline


Registered: 07/04/17
Posts: 55
Loc: In
Hello, I am new.

This is a Chevy 1500 crew cab half ton, 2012 5.3L. I find it hard to find specific info on the additive question. the VIN code does not tell me if it's locking or limited slip. It only tells me 3:42 ratio. I have read where someone on here said all GM after a certain date uses NO additive.
My father and I serviced my rear diff, we put Mobil 1 synthetic 75w90 and NO additive. I don't hear any noise out of it; did we do right by not using a friction modifier?


Edited by SquirrelMan (07/04/17 07:41 PM)

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#4449792 - 07/04/17 07:41 PM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
userfriendly Offline


Registered: 06/03/03
Posts: 2630
Loc: LaFinDuMonde


Edited by userfriendly (07/04/17 07:49 PM)

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#4449796 - 07/04/17 07:46 PM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
SquirrelMan Offline


Registered: 07/04/17
Posts: 55
Loc: In
Thanks for that fast response. Much appreciated

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#4449803 - 07/04/17 07:55 PM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
SquirrelMan Offline


Registered: 07/04/17
Posts: 55
Loc: In
So I do have the G80 locking differential? That's good info to know. Confusing on the web if you're not a diff expert.

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#4449810 - 07/04/17 08:01 PM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
Kibitoshin Offline


Registered: 04/19/16
Posts: 696
Loc: Kaiōshinkai
Check the RPO codes in the glovebox if you have the "G80" RPO code. These trucks either have an open or auto locking diff from the factory where they don't need additional LS additives.
_________________________
Shin Gekiretsu Shin'ou'hou
01 Toyota Tundra 2WD V8 4.7L - 170k mi
02 Chevy Silverado C1500 V8 5.3L 154k mi

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#4449818 - 07/04/17 08:13 PM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
SquirrelMan Offline


Registered: 07/04/17
Posts: 55
Loc: In
I most certainly do have the G80 RPO code; this forum is awesome. It sure helps to talk with knowledgeable people in this field. Thank you very much. To both of you.

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#4449825 - 07/04/17 08:18 PM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
userfriendly Offline


Registered: 06/03/03
Posts: 2630
Loc: LaFinDuMonde
One more little tid-bit; The Max-Trailer option gives you the bigger 9.76" diff.
3.76 with the 6 speed, 3.42 & 3.23 with the 8 & 10 speed 90Es.

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#4449845 - 07/04/17 08:36 PM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
SquirrelMan Offline


Registered: 07/04/17
Posts: 55
Loc: In
That's good to know... Thanks

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#4450059 - 07/05/17 05:09 AM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
Char Baby Offline


Registered: 05/25/05
Posts: 10024
Loc: ROCHESTER, NY
Maybe your rear diff doesn't require an additive however, the synthetic Mobil 1 75W90 LS that you put in your differential already carries the limited slip additive hence the "LS" designation.

Also if it's any consolation, using the "LS" additive in a differential that doesn't require it, won't hurt anything either! : )


Edited by Char Baby (07/05/17 05:15 AM)
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#4450063 - 07/05/17 05:26 AM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
4WD Offline


Registered: 09/21/10
Posts: 6390
Loc: Texas
Used that on several of those diffs through the years ... Delvac 1 now & some Delo on deck ...

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#4450125 - 07/05/17 07:47 AM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
barkingspider Offline


Registered: 12/22/13
Posts: 2049
Loc: socal
My escalade has the G80 and it does NOT need the limited slip additive in the rear diff
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#4450155 - 07/05/17 08:21 AM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: barkingspider]
4WD Offline


Registered: 09/21/10
Posts: 6390
Loc: Texas
Same - ran several G80's off M1 ... in fact cured cornering chatter in one ...
My current G80 went 40k on it before D1 went in ... that fluid looked new

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#4450440 - 07/05/17 01:41 PM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
BrianF Offline


Registered: 02/25/15
Posts: 551
Loc: Sask, Canada
My trailblazer has the G80. It is running Amsoil 75w90 without any additive. 5 years on this oil and it is as smooth as it ever was.
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1993 GMC 1500. It has oil and still runs

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#4450795 - 07/05/17 08:42 PM Re: GM 2012 AAM 8.6" rear diff need additive? [Re: SquirrelMan]
SquirrelMan Offline


Registered: 07/04/17
Posts: 55
Loc: In
Thanks for all the replies; great information. If any questions arise when we service the transfer case and front diff; I know where to come. Thanks a million.

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