GM gov-lock LSDs don't require the additive.

I just used the cheap 80w90 lube. I think it was Havoline or even AutoZone's house brand. This truck is old, has a ton of miles, and likely won't be around for long. I just needed cheap lube to get it back on the road with no drips in the garage.

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am

Gov Locs DO require additive. Any Clutch Style Posi requires it. Gm Part number you need is 992694. I even just checked my Gear Centre Parts Manual. Its a must. You can use the Ford Racing stuff to, M-19546-A1.

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2016 Dodge Charger Scat Pack 392
3.09's 8 Speed Auto
04 GTP

I highly doubt it has a LSD, unless it's a Z71. Most normal 4x4's didn't, AFAIK. I know my 98 didn't, and most trucks of that era didn't.

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Bye Bye:

RIP sandrock

depends on the year/towing package too Ed, 3.42 LSD is pretty common as well as 3.73

I believe the RPO code is G80 or something like that for a 3.42

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2000 ssei gone but not forgotten

Current fleet:
2009 G8 v6, 2009 Avalanche LTZ, 2013 Volt

I know my Tahoe had 3.73's with an open diff. Thing was a one wheel wonder. IIRC, the code was GT4, but I could be wrong.

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Bye Bye:

RIP sandrock

My 94 2door Yukon with a tow package had a Gov-Lok. Non-Sport or GT

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My 95 suburban

GT4 ; AXLE REAR 3.73 RATIO
G80 ; AXLE POSITRACTION LIMITED SLIP

Yes, you're right it is the G80 RPO code. And, I do have it.

Based on what I've been told from all the people at the GM truck forum, you do NOT need the additive. They said whenever they replace a gasket or fluid they just top it off with the cheap stuff off the shelf (80W90 in this case).

Honestly, I probably won't bother with the additive. The truck has 214,000. The rear diff is original. If it goes out, it goes out. I don't think it'd be from a lack of additive. The leak has subsided too. Now, I just have a really bad rear main seal leak.

Just gonna drive her the way she is for another year or so...

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am

Thats odd that they would tell you that it isn't required lol, it cost 5 bux, and is a cheap insurance policy. At that kinda mileage, hard to say what kinda shape the clutches are in. Torsen style LSDs are the only type that don't require it.

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2016 Dodge Charger Scat Pack 392
3.09's 8 Speed Auto
04 GTP

Hmm... for 5 bucks, my mind could be changed. lol If it doesn't need it (based on what they're saying) would it do any harm in having it in there?

Is it a dealer-only item?

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am

No, it's just an additive, available at any parts store. You may have to drain some of the fluid you put in, however.

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Bye Bye:

RIP sandrock

Its called a friction modifier.

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How many ounces is it?

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am

comes in the same size bottle as Supercharger oil. you can buy it at most auto parts stores, Napa, Autozone..maybe...
Gm under that number i gave you, ford under the other number i gave you.

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2016 Dodge Charger Scat Pack 392
3.09's 8 Speed Auto
04 GTP

The main purpose of the additive is to promote slippage of the discs during differential movement ie. turns, in order to prevent chatter and reduce heat build up.

It is required with all clutch, friction disc type limited slips.
Can't use it in our trani's with ATF. Our discs are way too small to matter.

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2000 SSEi - SilverBullet - 78,000 kms, 4" "straight shot" custom headlight ram air inlet, TOGs, 1.9's, Lsd, 2.9-3.4"MPS 10-15 psi, Ported GenV, EGR eliminated, OR pushrods, oil volume kit, trani cooler & shift kit, Titanium retainers, 90 lb springs, 160 Stat, 42# injectors, Fuel pump voltage increase, Wideband O2, 3" to dual 2 1/2" Magnaflows, Snow Meth/water injection, after SC temp gauge, 255/50WR17, timing commander set 15-18*@WOT, 2 speed Fan over-ride, disabled DRL, Solid motor mount, Meziere Electric water pump, adjustable fuel pressure regulator, Drilled & slotted rotors/ceramics, GXP sway bars and STB, Upgraded and rebuilt transmission with ZZP 2500 rpm stall TC, Pioneer Bluetooth stereo with sub and 800 W amps, PB 13.5 quarter, (April 2014 car of the month)

I don't think the G80 is a clutch based limited slip, but an actual locker, which is why it doesn't require a friction modifier.

I have a friend with a Tahoe that has broken three of them in the last few months because they aren't that strong off road, the most recent was about two weeks ago and we ordered him a Detroit TruTrac diff. When we were looking at the G80 diff, I didn't see any clutches anywhere, only some springs, weights, and the locking teeth.

( not saying for you to get a Detroit, just saying what he did )

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Ryan

2003 Bonneville SSEi - The Black Mirror SOLD!
2002 Bonneville SE - The Mutt Complete 2004 SLE interior, drivetrain, and body harness swap, ECC swap, HUD swap, black GXP wheels, GXP headlights and tinted tails - SOLD
2003 BMW 540i M Sport, 2001 BMW X5 4.4i, 2010 GMC Acadia, 2017 Grand Design Imagine 3150BH
1982 Cutlass Supreme - The fun one

Isn't the G80 an electronic locker? I know the one in our Duramax powered truck is.

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Bye Bye:

RIP sandrock

g80 has been the rpo code for years. it might have been upgraded to electronic but it hasn't always been

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2000 ssei gone but not forgotten

Current fleet:
2009 G8 v6, 2009 Avalanche LTZ, 2013 Volt

There's nothing electronic about mine.

Matt any comments on what Ryan said? That's the same thing I was told at the GMtruckforum.com too.

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am

After doing some more looking, it seems that there IS clutches with the G80 diff, they are behind the axle gears.

My apology for the misinformation earlier

There is an exploded view of a G80 in this thread http://www.dieselplace.com/forum/showth ... ?p=2522117

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Ryan

2003 Bonneville SSEi - The Black Mirror SOLD!
2002 Bonneville SE - The Mutt Complete 2004 SLE interior, drivetrain, and body harness swap, ECC swap, HUD swap, black GXP wheels, GXP headlights and tinted tails - SOLD
2003 BMW 540i M Sport, 2001 BMW X5 4.4i, 2010 GMC Acadia, 2017 Grand Design Imagine 3150BH
1982 Cutlass Supreme - The fun one