2008 Silverado 3500 LMM diff oil change

[bertram31]

Can't locate the thread that talked about changing the diff oil and transfer case oil soon after break-in period. What is recommended. I currently have 1400 miles and am getting ready to drive back to Virginia from Florida. Should I wait until I get back or should I change it now. The drive back will be approx 900 miles. Thanx in advance for your advice. r/ rea

[DmaxMaverick]

5000 driving only miles, or 500 towing miles, whichever comes first. You should be fine until after your trip. Are you towing on this trip? If you haven't towed yet, and are towing for this, I'd do it as soon as you get to VA. You don't want to change it too early. If you do, you should do it again once you get your towing miles on it. It is not that critical, but is important to address it, rather than just go by the manual and wait 50K miles. Once you pull the plug and see what comes out, you'll see why. Also, for the first 500 miles of towing, take it easy. The gears need to be heat cycled (work hardened), but don't allow them to get too hot. This time of year, you should stop about every hour of driving and let it cool a bit. Sooner for heavy towing, grade driving, or high speed highway, longer for flat land moderate speed non-towing. You should be able to get some idea of what you need to do once you make your first stop and put your hand on the cover. It should get hot enough (immediately after a stop) you can place your hand on cover for a couple seconds, then cool enough once you can leave your hand on. Not scientific, but will get you in the ballpark. If you don't feel like handling the diff, just drive an hour and sit 10 minutes before continuing. Longer drive time for city or slow driving. If you have an infrared temp probe, the diff cover needs to get above 200°F, and cool off to about 140°.

[DmaxMaverick]

Just read your other post. If you towed your TT for those 900 miles, I suggest you change the lube before returning. Towing 900 miles at 70 MPH on a new diff can cook the paint right off the cover. You'll be OK, but I'd change it soon.

[bertram31]

Thanx DmaxMaverick for your advice. I made the trip down to Florida empty not towing anything. I have made two short trips towing my 30 ft camper trailer but those distances were approx 60 miles one way to camp. Now reaching approx 3500 total miles and will soon replace the diff and TC oils. Had a great cruise going down to Florida. This truck is a real joy to drive. r/rea