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#2777277 - 10/19/12 09:54 AM gear oil selection for 02 tahoe
macdole99 Offline


Registered: 03/09/08
Posts: 137
Loc: Alabama
hey guys i just purchased an 02 tahoe 4x4. im in the process of changing all the fluids out. my manual goes for 80w90 in the front diff and 75w90 in the rear. any suggestions? i was thinking if going with the mobil 1 75w90 but have heard that the ls additive in is isnt good for my truck and then i have heard its fine. any ideas guys? thanks!!
_________________________
2001 Infiniti i30 267k (R.I.P)
1999 altima 235k (maxlife)
2002 tahoe 175k (ultimate durabilty)
2002 town and country 170k (maxlife)

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#2777289 - 10/19/12 10:03 AM Re: gear oil selection for 02 tahoe [Re: macdole99]
JGW Offline


Registered: 02/23/12
Posts: 223
Loc: New York
I just changed the rear diff fluid in mine with Mobil 1 75w90. So far so good.
_________________________
2002 Jetta TDI. 203k RT
2011 Toyota Matrix 29k
1998 Chevy Tahoe 290k M1
1985 Fiat Spider 34k
1984 Nissan Turbo 300ZX UD

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#2777294 - 10/19/12 10:09 AM Re: gear oil selection for 02 tahoe [Re: macdole99]
macdole99 Offline


Registered: 03/09/08
Posts: 137
Loc: Alabama
i just called the mobil tech support they also confirmed it would be ok but told me not to use it in the front which requires 80w90. he said the additives in it could cause a leak
_________________________
2001 Infiniti i30 267k (R.I.P)
1999 altima 235k (maxlife)
2002 tahoe 175k (ultimate durabilty)
2002 town and country 170k (maxlife)

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#2777306 - 10/19/12 10:19 AM Re: gear oil selection for 02 tahoe [Re: macdole99]
JGW Offline


Registered: 02/23/12
Posts: 223
Loc: New York
I guess that makes Mobilube HD the winner. Enjoy the truck.
_________________________
2002 Jetta TDI. 203k RT
2011 Toyota Matrix 29k
1998 Chevy Tahoe 290k M1
1985 Fiat Spider 34k
1984 Nissan Turbo 300ZX UD

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#2777442 - 10/19/12 12:37 PM Re: gear oil selection for 02 tahoe [Re: macdole99]
Rand Online   content


Registered: 08/20/03
Posts: 7345
Loc: Akron,Ohio
Originally Posted By: macdole99
i just called the mobil tech support they also confirmed it would be ok but told me not to use it in the front which requires 80w90. he said the additives in it could cause a leak


Wow that doesnt sound right.. sounds like regular mechanic rumortruth.

whats it going to make leak?

every type of seal in the front is also in the back.....


Edited by Rand (10/19/12 12:38 PM)
_________________________
2011 Subaru Forester X Prem. 5MT

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#2779235 - 10/21/12 02:39 PM Re: gear oil selection for 02 tahoe [Re: macdole99]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
Originally Posted By: macdole99
i just called the mobil tech support they also confirmed it would be ok but told me not to use it in the front which requires 80w90. he said the additives in it could cause a leak


Cause a leak? From a factory rep?? Doesn't sound right to me.

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#2779287 - 10/21/12 03:45 PM Re: gear oil selection for 02 tahoe [Re: macdole99]
Loobed Offline


Registered: 07/20/07
Posts: 3742
Loc: Northern California, USA
Use 75w-90 in both the front and back, unless you already have some 80w-90 and want to use it up in the front. I would suggest Amsoil Severe Gear if you can find it locally. It is one of the better gear oils for your truck. You should also have some limited slip additive on hand in case your rear differential starts to make noise. Adding LS additive lessens the life of the fluid. I added some GM Limited Slip additive to Amsoil SVG and it went beyond its useful life faster than the front SVG oil. The oil with the LS additive showed less wear, but a very high TAN.

I don't recommend Valvoline or Mobil-1. I tried both in my Sierra Z-71 and they caused chattering. The Valvoline was worse. You can try Eneos 75w-90. I have that in the front differential right now. This is about as cheap as you can find it and it has free shipping Eneos 75w-90 - 5qts 5 quarts will do both the front and the back.



Edited by Loobed (10/21/12 03:47 PM)
_________________________
Engine: 2001 GM 5.3L LM7
Current Fill: Valvoline Synpower 5w-30 w/Pure-One PL25288 filter

I.M.N Oil Enthusiast

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#2779470 - 10/21/12 07:50 PM Re: gear oil selection for 02 tahoe [Re: macdole99]
ledslinger Offline


Registered: 06/21/09
Posts: 839
Loc: Missouri
There's an O-ring on the screw in plug where the front diff vent hose attaches that isn't synthetic oil proof. There is a replacement screw in plug that comes with a synth proof O-ring. I think the original plug is white and the replacement is black. It's on the driver's side.

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#2779500 - 10/21/12 08:23 PM Re: gear oil selection for 02 tahoe [Re: ledslinger]
endeavor to persevere Offline


Registered: 04/10/05
Posts: 443
Loc: Middle Tennessee
If it has the G80 locking diff,
Heres what GM says about the truck G80

***Important: Installing any friction modifier causes the clutch pack in the locking differential to slip and miss engagement.

A fluid flush can often remove debris that is a contributor to clutch chatter. Adding friction modifier additive can cause a loss of locking differential functionality***

heres what the manufacturer of the G80 says

"From Mr. Ralph Holmquist of Eaton, the maker of the locking differential:
"The maintenance schedule for the rear axle was developed by American Axle &
Manufacturing and GM truck based on multiple tests. The Eaton locker does
not require additional maintenance nor does it add heat to the lube. The
lube will darken due to the carbon wear on the clutch surfaces, much the
same as a disc brake pad & rotor. This does not damage axle components such
as seals or bearings. However, a new axle can produce excessive
temperatures (plus 350 degrees F) due to the ring & pinion breaking in that
will break the lube additives down. Avoid high loads, trailer towing and
high speed extended driving during the initial break in of the vehicle.
After the break in period axle temps will level at a much lower figure.
Lube changes are a good idea because the additives are replenished and
contaminates such as casting sand are eliminated. The axle is filled at the
factory with a synthetic 75w90 GL5 rating made by Texaco under part # 2276.
The GM service # is 12378261. This is the only lube we have done extensive
testing with to insure locker compatibility. The only negative to using one
of these other lubes is an increased potential for clutch chatter. This
really doesn't hurt anything and can be corrected by changing the lube. I
noticed in the latest GM owners manual the term "or equivalent" when
referring to the lube specification. Look for a GL5 rating on the bottle to
make sure the ring & pinion, seals & bearings are protected. Limited slip
additive is not needed
."The following information outlines the type of
rear axle lubrication utilized in GM Truck axles.
I. Fluid Type
II. The 1500, 2500 and 3500 GMT 800 Trucks utilize SAE 75W-90 Synthetic Axle Lubricant. The GM part number is 12378261 and the specification is 9986115.
_________________________








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#2779548 - 10/21/12 09:34 PM Re: gear oil selection for 02 tahoe [Re: endeavor to persevere]
Loobed Offline


Registered: 07/20/07
Posts: 3742
Loc: Northern California, USA
Originally Posted By: endeavor to persevere

... The only negative to using one of these other lubes is an increased potential for clutch chatter.


That is what I found. I thought the factory lube was the best, but it was 2.5 times the cost of other lubes. LS additive isn't needed, but it wont damage the rear end (or it shouldn't). It just doesn't allow the clutches to lock up as good. This is almost irrelevant for street use. A Locking rear end is only useful in the dirt, mud, or snow.
_________________________
Engine: 2001 GM 5.3L LM7
Current Fill: Valvoline Synpower 5w-30 w/Pure-One PL25288 filter

I.M.N Oil Enthusiast

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#2779550 - 10/21/12 09:35 PM Re: gear oil selection for 02 tahoe [Re: ledslinger]
Loobed Offline


Registered: 07/20/07
Posts: 3742
Loc: Northern California, USA
Originally Posted By: ledslinger
There's an O-ring on the screw in plug where the front diff vent hose attaches that isn't synthetic oil proof. There is a replacement screw in plug that comes with a synth proof O-ring. I think the original plug is white and the replacement is black. It's on the driver's side.


Do you have a part number?
_________________________
Engine: 2001 GM 5.3L LM7
Current Fill: Valvoline Synpower 5w-30 w/Pure-One PL25288 filter

I.M.N Oil Enthusiast

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#2780424 - 10/22/12 06:50 PM Re: gear oil selection for 02 tahoe [Re: ledslinger]
Loobed Offline


Registered: 07/20/07
Posts: 3742
Loc: Northern California, USA
Originally Posted By: ledslinger
There's an O-ring on the screw in plug where the front diff vent hose attaches that isn't synthetic oil proof. There is a replacement screw in plug that comes with a synth proof O-ring. I think the original plug is white and the replacement is black. It's on the driver's side.


Do you know the size of the O-ring?

A complete new plug (white) with o-ring costs $25. If I new the size, I could probably get a silicone o-ring for a few dollars.
_________________________
Engine: 2001 GM 5.3L LM7
Current Fill: Valvoline Synpower 5w-30 w/Pure-One PL25288 filter

I.M.N Oil Enthusiast

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