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Fluid for G80 rear end in 02 silverado? #4652526
01/31/18 07:52 PM
01/31/18 07:52 PM
Joined: Jul 2016
Posts: 168
EasTn
Sealbilly Offline OP
Sealbilly  Offline OP
Joined: Jul 2016
Posts: 168
EasTn
Can't find a definite answer. Rear end code says my truck has a G80 limited slip 342 gear differential. But have read not to use fluid with LS additive, other places say yes use LS additive. Even read a notice from chevy saying not to but have heard that a new notice has been put out since then. It calls for synthetic 75w90 but since idk what the heck to put in it I opened her up sprayed her out with parts cleaner and refilled with 80w90 conventional valvoline. Two quarts without LS additive and almost a whole nother quart with LS additive. Since I cleaned it out I will just drain and refill if I have find out what in the world is supposed to be used in it.

Anyone know for sure?

Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4652597
01/31/18 08:42 PM
01/31/18 08:42 PM
Joined: Dec 2013
Posts: 2,450
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline
Joined: Dec 2013
Posts: 2,450
Fort Worth, Texas
You "can" run a LS fortified fluid, But technically it doesn't call for it.

Mobil Delvac 1 75w90 or Redline 75w90NS are the fluids I would run in a Gov-Loc.


The LS gear oils don't usually have enough LS additive in them for aftermarket high performance clutch type posi's.....I don't think "most of a quart" will matter.......

Last edited by clinebarger; 01/31/18 08:45 PM.

2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4652600
01/31/18 08:44 PM
01/31/18 08:44 PM
Joined: May 2006
Posts: 1,416
Grand Rapids, MI
WishIhadatruck Offline
WishIhadatruck  Offline
Joined: May 2006
Posts: 1,416
Grand Rapids, MI
I think it is a locker, not a clutch type limited slip. So, it does not need the LS additive, but being in the fluid will not affect it. You should be fine. I think the GM fluid calls for synthetic however as you state. I prefer Amsoil 75W-110. If you're not towing, not having synthetic probably won't hurt. If you tow, better put the synthetic in.


1996 Buick Roadmaster Wagon
2014 Cruze Eco Manual
2003 2500 Suburban, 8.1L
Re: Fluid for G80 rear end in 02 silverado? [Re: WishIhadatruck] #4652605
01/31/18 08:48 PM
01/31/18 08:48 PM
Joined: Dec 2013
Posts: 2,450
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline
Joined: Dec 2013
Posts: 2,450
Fort Worth, Texas
Originally Posted By: WishIhadatruck
I think it is a locker, not a clutch type limited slip. So, it does not need the LS additive, but being in the fluid will not affect it. You should be fine. I think the GM fluid calls for synthetic however as you state. I prefer Amsoil 75W-110. If you're not towing, not having synthetic probably won't hurt. If you tow, better put the synthetic in.


While it is a technically a Locker.....It does have Clutches, They are just never engaged during a turn & don't need the Anti-Chatter LS additive.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4652674
01/31/18 09:47 PM
01/31/18 09:47 PM
Joined: Jul 2016
Posts: 168
EasTn
Sealbilly Offline OP
Sealbilly  Offline OP
Joined: Jul 2016
Posts: 168
EasTn
Thanks gentlemen. I don't think it is locking the way it should as it sometimes is a one wheel wonder even in a strait line.

Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4652703
01/31/18 10:19 PM
01/31/18 10:19 PM
Joined: Dec 2013
Posts: 2,098
socal
barkingspider Offline
barkingspider  Offline
Joined: Dec 2013
Posts: 2,098
socal
I have had and still have trucks w the g80 rear diff and they do not require LS fluid. You can use any 75w90 or 80w90 in it. I have used both types and it ran normal zero problems


06 Cadillac Escalade Ext
17 Cadillac ATS (wife)
05 Toyota Camry (daughter)
11 GMC Canyon off-road (daily)
Re: Fluid for G80 rear end in 02 silverado? [Re: clinebarger] #4652706
01/31/18 10:25 PM
01/31/18 10:25 PM
Joined: Sep 2010
Posts: 7,496
Texas & Global
4WD Offline
4WD  Offline
Joined: Sep 2010
Posts: 7,496
Texas & Global
Originally Posted By: clinebarger
You "can" run a LS fortified fluid, But technically it doesn't call for it.

Mobil Delvac 1 75w90 or Redline 75w90NS are the fluids I would run in a Gov-Loc.


The LS gear oils don't usually have enough LS additive in them for aftermarket high performance clutch type posi's.....I don't think "most of a quart" will matter.......


Using Mobil Delvac 1 in my G80 for two years now smooth as silk and pulls on both wheels in sand/dirt/mud


2018 Chevy 1500 Z71 4WD
2017 Chevy Tahoe LT 4WD
2014 Fusion Hybrid Titanium
2013 Cruze LTZ - RS Turbo
Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4652714
01/31/18 10:35 PM
01/31/18 10:35 PM
Joined: Nov 2017
Posts: 381
North of you Idaho
KneeGrinder Offline
KneeGrinder  Offline
Joined: Nov 2017
Posts: 381
North of you Idaho
I've been using mobil 1 75w90 ls syn front and rear in mine for 10 years. G 80 rear.

Mine drives all four tire till one spins in front, then I just have three and it turns hard!

Last edited by KneeGrinder; 01/31/18 10:40 PM.

08 Tribeca 86k PUP 5w30 wix
06 Accord Hybrid 134k PPHM 0w20 wix
02 Chevy k3500 99k Delvac 1 esp 5w40 wix
00 F350 136k Delvac 1300 15w40 wix
Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4652739
01/31/18 11:06 PM
01/31/18 11:06 PM
Joined: Dec 2013
Posts: 2,450
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline
Joined: Dec 2013
Posts: 2,450
Fort Worth, Texas
Originally Posted By: Sealbilly
Thanks gentlemen. I don't think it is locking the way it should as it sometimes is a one wheel wonder even in a strait line.


How do you know it still has it's Gov-Loc? It wouldn't be the first 8.5"/8.6" differential to have catastrophic failure of the Eaton Governor Locker & a open differential installed.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4652965
02/01/18 09:40 AM
02/01/18 09:40 AM
Joined: Dec 2002
Posts: 1,614
North Carolina
Rat407 Offline
Rat407  Offline
Joined: Dec 2002
Posts: 1,614
North Carolina
I run AMSOIL's Severe Gear 75w-90 in my 02's diffs, I tow and have 177k on the vehicle. Sent a sample off that the fluid had 90,516 miles on it.



2002 Silverado 5.3 0w-20 AMSOIL
Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4653157
02/01/18 12:47 PM
02/01/18 12:47 PM
Joined: Mar 2013
Posts: 904
NY
joegreen Offline
joegreen  Offline
Joined: Mar 2013
Posts: 904
NY
If its a gov lock locker you do not need a limited slip fluid. There are no clutches in that type of locker.


1978 Chevrolet k20
Engine: Delo 10w30xle
Transmission: Castrol transmax dex/merc

1984 Mercedes-Benz 300 turbo diesel
Engine: Delo 400 15w40le
Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4653897
02/02/18 12:08 PM
02/02/18 12:08 PM
Joined: May 2012
Posts: 5,675
Fort Lauderdale, FL
DoubleWasp Online content
DoubleWasp  Online Content
Joined: May 2012
Posts: 5,675
Fort Lauderdale, FL
G80 diffs must have changed at some point. All of mine have metal warning tags on them that additive must be used.


07 Lincoln Navigator M1 0w-40/FU
68 Charger R/T / Supercharged 440 VR1/DBL7349
07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
17 Maserati GranTurismo Cabrio
Re: Fluid for G80 rear end in 02 silverado? [Re: Sealbilly] #4654015
02/02/18 03:12 PM
02/02/18 03:12 PM
Joined: Feb 2013
Posts: 3,340
Central Virginia
Silverado12 Offline
Silverado12  Offline
Joined: Feb 2013
Posts: 3,340
Central Virginia
I have a 2012 Silverado and am using straight non-synthetic 80W-90 in it and I tow heavy stuff too. Works well from what I can tell. FWIW mine doesn't have any warnings on it.

Last edited by Silverado12; 02/02/18 03:12 PM.

12 Chevy Silverado ext. cab LS, 2WD 4.3 auto
18 Mustang GT 5.0 auto
07 Harley Dyna Street Bob 96 c.i. 6 sp.
00 Mustang GT auto
Re: Fluid for G80 rear end in 02 silverado? [Re: joegreen] #4654058
02/02/18 04:24 PM
02/02/18 04:24 PM
Joined: Dec 2013
Posts: 2,450
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline
Joined: Dec 2013
Posts: 2,450
Fort Worth, Texas
Originally Posted By: joegreen
If its a gov lock locker you do not need a limited slip fluid. There are no clutches in that type of locker.


They do use clutches, But you are correct on them not needing LS additive.



2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: Fluid for G80 rear end in 02 silverado? [Re: DoubleWasp] #4654121
02/02/18 05:23 PM
02/02/18 05:23 PM
Joined: Aug 2004
Posts: 1,405
VA
Rhymingmechanic Offline
Rhymingmechanic  Offline
Joined: Aug 2004
Posts: 1,405
VA
Originally Posted By: DoubleWasp
G80 diffs must have changed at some point. All of mine have metal warning tags on them that additive must be used.


My understanding is that G80 is an option code. Depending on the axle or vehicle, that could mean the mechanism is either a limited-slip or a gov-lock.

One of my earliest posts was about the arcane GM spec number for axle fluid in my 2001 Silverado. It had the grape-scented special sauce from the factory. I ended up replacing it with Amsoil Severe Gear 75W-90, and the locker has continued to work for the last 70,000 miles.

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