Break in difference

This from my 2014 Chevy Duramax Owner's Manual:
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Do not tow a trailer during the first 800 km (500 mi) to prevent damage to the engine, axle,or other parts..Then during the first 800 km(500 mi) of trailer towing, do not drive over 80 km/h (50 mph) and do not make starts at full throttle.

I found this information after I towed the trailer, and I was over 1000 miles then. oops! But, I also never towed more than 50-55 mph though, as the first 2 or 3 camping trips we never drove interstates.

Truck now 3 years later, and seems to be just fine.

4x4ord wrote:
As was mentioned break in is for the rear end but I've never heard of anyone with a noisey rear end on account of putting his truck to work on day 1. Pulling a big RV down the road at 60 mph might require 100 or 110 HP. Cruising empty at 75 mph requires around 60 hp... Not a big difference in my mind.

I had to replace the ring and pinion gears on my Dodge/Ram before 70k miles due to noise. Don't know for sure towing from day one was the issue or just defective. I make sure on new trucks since then I put 500 miles non- towing before heavy use.

Cummins is ready to tow right out of the box. In fact they want you to tow it's good for the engine.

different metals used in the final gear sets...

mostly for the long mile use... setting up the wear patterns...

not the engines...
cylinders and piston rings 'Seat' almost instantly
Micro polishing....

As was mentioned break in is for the rear end but I've never heard of anyone with a noisey rear end on account of putting his truck to work on day 1. Pulling a big RV down the road at 60 mph might require 100 or 110 HP. Cruising empty at 75 mph requires around 60 hp... Not a big difference in my mind.

Typically break in these days is for the Rear End Gears not the engine.

When I bought all my Ram trucks, they came home with about 50 miles on them, get 8,000-10,000 pounds strapped on, and get driven like it was stolen.

What colliehauler said.

ACZL wrote:
Okay so here's a question which comes to mind.

Most everyone says incl GM, Ford and Ram to run a new diesel at least 500-1,000 miles to break it in before towing. Now, go to a semi dealer and buy a new truck w/ 0 miles and wham, next day your strapping 40,000 lbs to it and bopping down the road at 65 mph.

What's the difference? :h

In my owners manual they stated the break in was for the rear differential gears, not the engine.

Tighter tolerances on the tractor motors and I am sure the rings are set when they dyno them.

Id have to find documentation but most all manuals state no break in required.