do you need to add limited slip additive to the rear end , when draining and refilling ?????? the truck has the locking rear diff . option !!
also i was told the rear diff holds 4 qts. ???? is that correct ????

thanx the05hd

No additive required. Make sure it is GL-5 rated. I can't remember exactly what it holds but IIRC it is a little over 3 quarts so you will be safe with 4.

do you have a owners manual?

called my stealer today ..... they said that it requires a additive !!!!!

not sure what they know or dont know ????????

any help ?????????????????????

the05hd

ya why ??????? does not say in thier !!!!! does yours !!!!!do you have a owners manual?

I wouldn't worry about an additive if it were me. If you experience chattering, then you can always add some to correct the problem.

Fill it to the bottom of the check hole with a quality GL-5 synthetic in 75-90W and don't worry about it. Some guys use 75-140W if they are constantly towing, but most should probably stick with 75-90W.

I'm using Mobil 1, but there are plenty of quality lubes out there. I personally don't feel that the GM specified "grape juice" is necessary, but do as you wish. A warranty absolutely should not be denied because you were using a GL-5 lube instead of "grape juice."

i don't have a owners manual here at school, but i would like to think it would be listed in the owners manual under capacities or fluids. even possably under specifications.

The specs for the rear locker do not require anti-slip additive. You can confirm this with Eaton if you want to. I think the info is on their web page. Actually, I think they might even recommend against it. They DO recommend additive for the limited slip, but this is a locker, not LS.

Here ya go. I highlighted it in BLUE.

<TABLE height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD width=58></TD><TD vAlign=top width="72%">
G - 80 Option - Eaton Locking Differentials



http://www.automotive.eaton.com/images/products/systems/lockingdiff.jpghttp://www.automotive.eaton.com/images/products/systems/lockingdiff1.jpg

<TABLE border=0><TBODY><TR><TD>Availability</TD></TR><TR><TD>¨ Standard Equipment on Dual Wheel 3500 Series trucks.<?XML:NAMESPACE PREFIX = O /><O:P> </O:P>

¨ Optional Equipment (G80 Order Code) on all GM two-wheel and four-wheel drive light trucks and sport utilities.<O:P> </O:P>

</TD></TR><TR><TD>Benefits</TD></TR><TR><TD>¨ Improved traction differentiates the vehicle relative to other rear wheel and four-wheel drive vehicles on the market.<O:P> </O:P>

¨ Functions as a limited slip differential during normal driving conditions; provides full axle lock when needed.<O:P> </O:P>

¨ Maintenance free; requires no lube additives.<O:P> </O:P>

¨ Enhanced towing and off-road performance.<O:P> </O:P>

¨ Patented carbon friction disc technology enhances performance and durability while reducing warranty claims.<O:P> </O:P>

</TD></TR><TR><TD>Principles of Operation</TD></TR><TR><TD>¨ Wheel speed difference (left to right) in excess of 100 RPM will cause a flyweight mechanism to open and catch a latching bracket.<O:P> </O:P>

¨ The stopped flyweight will trigger a self-energizing clutch system, which results in the cam plate ramping against a side gear.<O:P> </O:P>

¨ Ramping increases until both axles turn at the same speed (full lock), which prevents further wheel slip.<O:P> </O:P>

¨ At speeds above 20MPH, the latching bracket swings away from the governor and prevents lockup from occurring.<O:P> </O:P>

</TD></TR><TR><TD>Technical Specifications</TD></TR><TR><TD>¨ Automatic locking takes place within a fraction of a second, so smoothly that it is unnoticed by the average driver.<O:P> </O:P>

¨ Unlocking occurs automatically, once the need for improved traction is gone, and is unnoticeable to the average driver.<O:P> </O:P>

¨ Compatible with anti-lock brake systems.<O:P> </O:P>

</TD></TR></TBODY></TABLE>
</TD></TR></TBODY></TABLE>

thanx for the info !!!!!



the05hd

The GM 14x11.5 rear end which is commonly found in the Duramax hold exactly 3.6 liters (7.7 pints). Try using Lubrication Engineers ALMASOL 607 vari-purpose gear lubricant.
*Reduces over heating
*Non foaming
*outperforms synthetic oils
It's excellent product and you do not need to use any additives with it. If you decide to us an additve take a look at TORCO type G Limited slip friction modifier. It's actually made specifically for GM axles. It will reduce gear noise and chatter.
You can pick up LE rear end fluid at www.performanceproducts4trucks.com

Thanks
Al

I did my 05 2500HD CC Dmax and it took 4.1 qts.
I did my friends 04 2500HD 6.0 gas and it took 3.3 qts
The drain plugs were oriented differently on the 2 trucks. mine was vertical, his was at about 25deg angle ?
I know they change things from year to year.
Mine had only 2 1/2 qts in it from the factory. his was low as well.

the 6 liter o4 gasser uses different rearend than the 8.1 and the Duramax. I have both.

The factory seems to ship the trucks low on oil ,the 03 I had was over a quart low and my new 05 was delivered a 1 1/2 quarts low, the front diff was 1/2 quart low,but this should have been corrected during the pdi by the dealer,I quess this is one way to save money!

If you fill them to the drain plugs, like how I was used to on older vehicles, you'll make the axle seals leak.

Read the owners manual, it states a certain limit below the fill plug about 5/8" or so... for a reason.



6.0 gas motors use a 14 bolt, 10.5" rear. 8.1 and Dmax use the 11.5".

It took that much oil to fill to the correct level