2007 Gmc Sierra Diff. Fluid

[MarcoMtz]

I own a 2007 GMC (new body style) with a lim slip diff. now i called the dealer and they told me that the new trucks dont need the additive for the diff.. all i need is Synthetic Gear Oil 85_95W and no additive, thats only for classic body stile, i got my gears done today and they are asking me for the additive, and i told them what the dealer said, they are not giving me any warranty because of that.... can any one confirm the fluid type and does it need the additive ...?

[RyanbabZ71]

The additive hasnt been used since the GMT-400 trucks.

 

Do you have an owners manual in your glovebox? It states what the correct fluid is.

[MS3DALE]

As Ryan stated,you do NOT need any additive,nor does GM want you to use any,I've seen it do more harm than good.

Also,the GMT400 trucks didn't even require it. The only newer trucks that do is the Trailblazer SS's and Quadrasteer trucks,and GM has a fluid out for them that already has the proper additive in it,so even those do not require any additional additives.

[pm26]

If I am not mistaken, GM did not even offer limited slip differential in 1/2 ton pickups for 2007. Your truck differential, (G80 if so equipped), is a mechanical locking type, not limited slip. The factory oil used is synthetic oil. You can buy it at your GM dealer in 1 quart containers. No additional additives are required or recommended.

[dlstewart01]

The G80 installed in trucks has always been a mechanical locking diff and has never required an additive.. The only truck to get a limited slip was the Quadrasteer and it got a G86.

 

What GM says...

 

***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***

 

What Eaten, 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.