Towing

[Chevy Mike]

I just bought a 2022 Silverado 2500HD with the 6.6 gas engine. Can anybody tell me when i can start pulling my 8000 lb camper with no restrictions. Owners manual says on the 1st towing trip to not go over 50 mph. By the time we go camping we should have around 1200 miles on the truck. 50 mph is a little slow considering speed limit is 65 mph on way down to the shore. I dont want to cause an accident. Thank you, Mike W.

[Thankful]

I don't know what your manual says, but that's where I'd go to find out.  Years ago, the standard break in mileage was 500 miles before you towed.

[newdude]

56 minutes ago, Chevy Mike said:

I just bought a 2022 Silverado 2500HD with the 6.6 gas engine. Can anybody tell me when i can start pulling my 8000 lb camper with no restrictions. Owners manual says on the 1st towing trip to not go over 50 mph. By the time we go camping we should have around 1200 miles on the truck. 50 mph is a little slow considering speed limit is 65 mph on way down to the shore. I dont want to cause an accident. Thank you, Mike W.

 

 

Heat.  Diffs produce lots of heat during the first 500mi of break in.  They also will produce lots of heat during initial towing.  I'd get the trailer hooked up after you put 500mi on it to get it "broke in" with a trailer, and then before you do your camping trip change the oil as it also says.  

[ShotgunZ71]

When my 2020 was new, it sure had a pile of various driving before the first tow. That happened between 500-1000 miles. Towed like normal, normal speeds, etc. Trucked performed great pulling a 42' 15000lb fifth wheel on that trip and multiple others.

[Another JR]

4 hours ago, newdude said:

 

 

Heat.  Diffs produce lots of heat during the first 500mi of break in.  They also will produce lots of heat during initial towing.  I'd get the trailer hooked up after you put 500mi on it to get it "broke in" with a trailer, and then before you do your camping trip change the oil as it also says.  

There’s a good reason the manual recommends not towing in the break in period, and it is primarily related to the differential. Heat is part of it but really a by-product of the break in process. However, it also aggravates the conditions during break in by thinning the oil.  

When the differential ring and pinion are new, the gear tooth contact area is very small, creating very high contact pressure. This causes oil film breakdown and surface wear, which eventually wears in the contact point, spreading the tooth contact pressure and reducing the local surface stress. If the differential is highly loaded before this wearing in has been allowed to slowly occur, the high local contact stress can cause spalling of the tooth surfaces at the contact point.
 

If spalling occurs, best case it will cause a noisy differential with reduced life, and worst case it can cause tooth failure due to the created stress concentrations. 
 

instead, you want to run the differential lightly loaded until the gear contact patches have worn in to some extent, spreading out the force and reducing the contact pressure. Once this has occurred to some extent, the gear teeth can withstand the higher load assocIated with towing. GM has recommended a particular minimum number of miles for this. More is better. 

[the wanderer]

No doubt you should follow GM's recommendations. But note that there is not a single guy who uses these trucks for work (landscapers etc) who give a seconds thought to "break in". They buy it off the lot one day and it's working hard the next day.

[Another JR]

Agreed. I was just explaining why you don’t want to do that and why you probably don’t want to buy a used truck from someone like that. If they weren’t pulling heavy weights up long climbs, and not applying max torque (like pulling a big boat out of the water) it probably is just fine.  There is a legitimate physical reason to break it in, though.