front and rear diff oil

snorydermb · October 4, 2006

Im getting ready to change front and rear diff and transfercase oil just wondering what everyone is using.

Roofer · October 4, 2006

I used Mobil 75-90 gear oil on my differentials. Make sure you use synthetic.

jake111 · October 5, 2006

I believe GM has a spec (9986115?) for the G80 that only their genuine "grape juice" 75W-90 synthetic lube meets (GM part# 12378261). Ok, I fell for it and I paid $26/qt.; parts guy pointed out the good deal I got off the $36 regular price (actually, he was very nice and I appreciated it, and told him so).

The yellow stuff that comes out of the front diff (at least mine) is very strange. I did grape juice but I think I would be just as well off with Mobil 1 or other GL-5 synthetic. BTW, if you have a pre-2004 truck and the front diff has a black vent cover, it's recommended that you go buy a white one from the dealer before switching to synthetic (looks like it was redesigned slightly).

I haven't done transmission or transfer case yet. For pre-2006, Allison Transynd is first choice followed by any Dexron III synthetic, followed by any Dexron III.

03HD · October 6, 2006

Mobil 1

dewfpo · October 9, 2006

I believe GM has a spec (9986115?) for the G80 that only their genuine "grape juice" 75W-90 synthetic lube meets (GM part# 12378261). Ok, I fell for it and I paid $26/qt.; parts guy pointed out the good deal I got off the $36 regular price (actually, he was very nice and I appreciated it, and told him so).

The yellow stuff that comes out of the front diff (at least mine) is very strange. I did grape juice but I think I would be just as well off with Mobil 1 or other GL-5 synthetic. BTW, if you have a pre-2004 truck and the front diff has a black vent cover, it's recommended that you go buy a white one from the dealer before switching to synthetic (looks like it was redesigned slightly).

I haven't done transmission or transfer case yet. For pre-2006, Allison Transynd is first choice followed by any Dexron III synthetic, followed by any Dexron III.

<{POST_SNAPBACK}>

X2

DEWFPO

slowpokebanshee · October 9, 2006

gm auto trak II in transfer case, and whatever you want in front and rear case....just keep it clean, never seen a problem due to wrong fluid type in differentials....suppose you could be the first, but if you look at the part numbers for say a 2005 half ton rear end, and say a 1988 half ton rear end......same bearings same ring and pinion, etc. what's the difference?

GMCWAYNE · October 9, 2006

You don't need autotrak fluid in the transfer case on a HD. Only on a half ton with the auto 4x4 feature. I used mobil 1 tranny fluid in my transfer case 2 quarts. I used mobil 1 75w90 in my front and rear differentials. 2 quarts front and about 3.75 quarts rear.

Paulie G · December 11, 2006

I believe GM has a spec (9986115?) for the G80 that only their genuine "grape juice" 75W-90 synthetic lube meets (GM part# 12378261). Ok, I fell for it and I paid $26/qt.; parts guy pointed out the good deal I got off the $36 regular price (actually, he was very nice and I appreciated it, and told him so).

The yellow stuff that comes out of the front diff (at least mine) is very strange. I did grape juice but I think I would be just as well off with Mobil 1 or other GL-5 synthetic. BTW, if you have a pre-2004 truck and the front diff has a black vent cover, it's recommended that you go buy a white one from the dealer before switching to synthetic (looks like it was redesigned slightly).

I haven't done transmission or transfer case yet. For pre-2006, Allison Transynd is first choice followed by any Dexron III synthetic, followed by any Dexron III.

<{POST_SNAPBACK}>

Tell me more about this black vent cover on the front differential, I'm due to change fluid soon.

Location, cost, etc...

Valsport · December 11, 2006

i never switched my black vent to a white one but i havent had a leak running synthetic in the front diff in 65k miles.

Buggle_96 · December 11, 2006

Mobil 1 75w90

Mattt · December 12, 2006

I havent looked in the manual yet, but is synthetic spec'd out? Seems like everyone here recommends synthetic. Is that because GM calls for synthetic?

Valsport · December 12, 2006

syn required by gm in rear, front not required.

Mattt · December 22, 2006

I'd like to change my rear diff fluid as my truck just rolled 90k, and I tow with it regularly. I havent gulped down the pricey GM or Mobil 1 gear lube yet.

I was at Walmart last night{unfortunately}, and noticed Super Tech has a full synthethic gear lube for $4 per quart. Anyone tried this stuff? Yeah, its not Mobil 1, but it seems like Ive heard good things about Super Tech motor oils {both dino and syn} in the past and on Bobs-the-oil-guy.com.

Comments anyone? Anyone used this Super Tech Syn gear lube?

cts2500hd · December 27, 2006

Amsoil gear fluid.

Dave in Mpls · December 29, 2006

I believe GM has a spec (9986115?) for the G80 that only their genuine "grape juice" 75W-90 synthetic lube meets (GM part# 12378261). Ok, I fell for it and I paid $26/qt.; parts guy pointed out the good deal I got off the $36 regular price (actually, he was very nice and I appreciated it, and told him so).

The yellow stuff that comes out of the front diff (at least mine) is very strange. I did grape juice but I think I would be just as well off with Mobil 1 or other GL-5 synthetic. BTW, if you have a pre-2004 truck and the front diff has a black vent cover, it's recommended that you go buy a white one from the dealer before switching to synthetic (looks like it was redesigned slightly).

I haven't done transmission or transfer case yet. For pre-2006, Allison Transynd is first choice followed by any Dexron III synthetic, followed by any Dexron III.

<{POST_SNAPBACK}>

Tell me more about this black vent cover on the front differential, I'm due to change fluid soon.

Location, cost, etc...

<{POST_SNAPBACK}>

Document ID# 1548733

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Subject: Info - Use of Synthetic Front Axle Lubricant For 4WD Vehicles Sold in Cold Weather Climates #03-04-19-001B - (09/03/2004)

Models: 2002-2004 Chevrolet Avalanche 2500, Silverado 2500/3500, Suburban 2500

2002-2003 Chevrolet Silverado 1500HD

2002-2004 GMC Sierra 2500/3500, Yukon XL 2500

2002-2003 GMC Sierra 1500HD

with Four-Wheel Drive and 9.25" Front Axle Assemblies and Built Prior to April 1, 2004

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This bulletin is being revised to update vehicle applications, part numbers and fluid fill information. Please discard Corporate Bulletin Number 03-04-19-001A (Section 04 -- Driveline/Axle).

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Important: This bulletin is intended for vehicles sold in very cold weather climates, especially those in Alaska and certain regions of Canada.

Important: This bulletin DOES NOT apply to vehicles built after April 1, 2004. Vehicles referenced above that were built after April 1, 2004 were manufactured with front axles containing synthetic axle lubricant and do not need to have the front axle fluid inspected or changed.

Front axles in the above-listed vehicles built before April 1, 2004 are manufactured with mineral-oil base axle fluid. Because of the 9.25" front axle assembly's internal design characteristics, there may be insufficient lubrication flow at very low ambient temperatures (-24°C (-12°F) or below). This may contribute to premature pinion bearing wear if a vehicle is driven extensively in very low ambient temperatures.

Important: Please be certain that PDI personnel know to perform the drain/refill procedure all year round (not just in the cold weather months).

New vehicles that are expected to operate extensively in 4WD in temperatures below -24°C (-12°F) should have their front axle fluid drained and refilled with synthetic axle lubricant during PDI or before delivery to the first retail customer.

Follow the Front Drive Axle Lubricant Replacement procedure found in the Service Manual (SI Document ID #673354). It is not necessary to flush the front axle assembly. Use Synthetic Axle Lubricant, P/N 12378261 or P/N 89021677 (Canadian P/N 10953455 or P/N 89021678 ). Each of these part numbers is the same axle lubricant, with differences in packaging only. Fill to a level between 6 and 9 mm (0.25 in to 0.375 in) below the bottom of the fill plug.

For vehicles that have the axle lubricant changed, the front axle vent hose connector assembly will need to be inspected.

Important: Front axle assemblies with a vent hose connector assembly that is white in color do not need to be changed.

If the vent hose connector is black in color, it will need to be changed so that the O-ring seal is compatible with the synthetic lubricant. Install vent connector, P/N 12479390 . Follow the Front Drive Axle Vent Hose Connector Replacement procedure in the Service Manual (SI Document ID #843184).

Parts Information

Part Number Description Qty

12378261 or 89021677

(Canadian P/N 10953455 or 89021678 ) Oil, Synthetic Gear 2

12479390 Connector, Axle Vent 1

Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation Description Labor Time

*F0011 Fluid, Axle and Differential (Front) - Drain and Fill 0.5 hr

Add To Replace Front Axle Vent Hose Connector 0.1 hr

*This is a unique labor operation number for use only with this bulletin. This number will not be published in the Labor Time Guide.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

Document ID# 1548733