2010 Rear End break in and lube

[bickford]

I've ordered a 2010 3500hd pickup for 5th wheel towing and am wondering about the proper rear-end lube (and additives) for gear-oil change after initial break in. I've read that this should be done at 500-1000 miles and I'd like to use the right stuff. The truck will have the G80 automatic locking differential and 4.10 gears.

The 2009 manual (online) says SAE 75W-90 Synthetic Axle Lubricant (GM Part No. U.S. 89021677, in Canada 89021678) meeting GM Specification 9986115 and doesn't mention an additive. It also doesn't say what the fluid capacity is...

I don't have the 2010 manual yet to read. Any comments?

Thanks!
Joel

[DmaxMaverick]

Getting a gasser? Otherwise, you'll get a 3.73 rear end ratio, which is the only ratio available with the Diesel. Or you ordered a Ford (oops).

I have seen no changes, proposed or otherwise, on the rear ends. The 2009 info you have is correct, and should be the same for the 2010. If you plan on full-time towing, and/or in very hot climate, you can also use 75-140 lube. Capacity is about 3.5 qts, and should be filled to about 1/2" - 3/4" below the fill hole, with the truck on a level surface.

In any case, the G80 option does not require any additive. Using L/S additive can, in some cases as I've seen, cause premature failure of the friction surfaces of this type diff. It's a locker, not a traditional limited slip in any way.

Good choice on the early service, in any case.

[bickford]

Getting a gasser?

I am getting the gasser. Based on http://www.pickuptrucks.com/html/2007/shootout/hdshootout5mpg.html (great article!!) it looks like the gasser will work fine.

Also, the likely (small) fuel mileage difference for 2010 doesn't seem to justify the huge cost difference...

Thank you for the info!

Joel

[bickford]

Does the current model have a rear end drain plug? If so, is it good enough to just drain and refill or is there a compelling reason to remove the cover?

Thanks!
Joel

[DmaxMaverick]

The 11.5" diff (equipped with any Allison and/or Duramax) has a drain plug. No reason I've seen to remove the cover. The drain is sufficiently thorough, and the plug is magnetic (be sure to clean it). I usually service the diff while it's hot (immediately after a hard drive), and jack each side to drain the axle tubes. It makes a difference. Just a drain/fill should take about 3.5 qts. When I do the jack/drain, it will take about 4 qts. I allow about 20 minutes of drain time for each side.

Just a note:
Depending on the gasser option, it may not have an 11.5" diff. If it has any tranny other than an Allison (later models, when the ZF 6 speed is not available), the diff will likely be a 10.5", and no drain plug. This is a bit foggy for 2010 M/Y, as I haven't seen one to verify, and the dealers won't know, either. The additive requirement (no additive recommended/required) is the same, regardless.

[DarylB]

Does the current model have a rear end drain plug? If so, is it good enough to just drain and refill or is there a compelling reason to remove the cover?

Thanks!
Joel

My dad's 2007 6.0L doesn't have a drain plug. It's the new style 10.5" 14 bolt setup, with the ribbed pumpkin, but alas, no drain plug (wtg GM!)

[WyoDutch]

I just completed my 1,000 mile break-in on my new 2009 GMC 3500 Duramax 4X4.
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Took it in yesterday for bumper to bumper eyeballing and change of all fluids and filters in the engine, transmission, transfer case and differentials.
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Yeah... I know, not really necessary (in most cases), but I've always switched the fluids at 1,000 miles on new vehicles... Just to flush out any grit or shavings that may have been loosened during the break-in period. I keep my vehicles for a looong time and always believe in starting them out right.
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I plan on switching to Redline synthetic diesel motor oil and Baldwin filters when the odometer rolls to 10,000. Haven't done any towing yet... but one of these days, will load the snowcat on the trailer and head up the mountain to temper the differentials, as recommended here on DP. Tow an hour, cooldown 15 minutes.. repeat.

The only issues of note (and it may be nothing), is a noise when I'm in 4WD and I back off the power. I hear what almost sounds like what you hear when a fanbelt is slipping. Last night, driving home, I hit about 40 miles of icy roads, so I popped it into 4WD and noted the noise as described. Slide it into 2WD and the noise disappears immediately.

My overall impression of the truck (Extended cab, SLT) is that GM and the UAW did a first class job on building it.

[Mark Rinker]

>>>
The only issues of note (and it may be nothing), is a noise when I'm in 4WD and I back off the power. I hear what almost sounds like what you hear when a fanbelt is slipping. Last night, driving home, I hit about 40 miles of icy roads, so I popped it into 4WD and noted the noise as described. Slide it into 2WD and the noise disappears immediately. >>>

If its a vibration you feel through your feet on the floorboards, that is a normal 4WD-ism. Every Silverado 4by that I've had since 1998 has the same feel through the feet, when engaged. However, if its a squeek or squwall like a fanbelt, then I'd dig in further...

Sounds like a meticulous break-in process. You'll get no argument from me on all that you are doing. My break-in process has been like this:

Buy truck on Monday. Tuesday throw all gear into truck, install e-brake controller. Wednesday hook 16K# of trailer and cargo behind it, drive 1200 miles or so. Repeat for 100K miles, with regular fluid changes.

Like a rock!

[WyoDutch]

I plan on keeping an ear/eye on it to see whether it's just a break-in noise or something more.
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This is my first Duramax/Allison unit, so there's a lot for me to learn and get familiar with.

[hapaschold]

i asked service manager about the 09 rear locker on my dmax,

reply was no 1000 mile service needed any more since eaton ? now pre wears the rears....

never read the owners manual yet..