We just bought a new 05 duramax and want to know the best break in for the motor and trans. Will do a lot of trailer pulling while going camping. Any suggestions? Thx

First off, welcome.

Second, it's likely you'll get all kinds of opinions on this, and mine is probably no better than any of the others.

I tend to take the "break-it-in-easy" approach. I try to vary engine speeds and load the engine in increasing amounts as I get a few more miles on the clock. While a lot of people recommend running the truck hard during the break-in phase, I tend to disagree. While this would actually be fine for the engine in my opinion, I think it's harder on differentials and transmissions. On a brand new truck, I don't like to pull a trailer for a few hundred miles for this reason. If it was a rebuilt engine in an otherwise "broken-in" truck, then I think it would be beneficial to load the engine this way.

Bottom line: I'm not too sure anybody has the "secret" to breaking equipment in the right way. I'm only 20, so I'm by no means the gospel, either.

I would recommend fairly short oil drains for the first few thousand miles in order to remove as much break-in debris as possible. I hope this helps ya out--congrats on the new truck!

G-,

Welcome aboard.

The Motor and Rear axle on these trucks are Real Tight.

I would not tow before 500 miles, then change the rear axle fluid, it Will be black. If you choose to change it your self (many of us do) perform a Search here and you will learn how to do it, if you don't aready know.

The motor is tight but very tough, 10 qt of oil to lube and cool it. I agree with the "KID" vary the RPM/Speed for a while, then Go For It.

You will receive Many inputs and they all have value.

These are my opinions.

Good Luck.

Idahofox

Search man, search. Works wonders.

If you'd like to chat, I'm over on Gilbert and McKellips...

Also make sure GM put enough fluids in the vehicle (differentials, tranny, oil, PS fluid, etc.) GM has been known to not fill the rear differential all the way. Welcome aboard and good luck with the new wheels.

I'll throw my .02 in on this one.

A quick list of do's and don'ts:

1.Don't let the engine idle for excessive periods of time (like more than 5 min, this includes idling in traffic) during the first 100 miles. Diesel's run cold especially when idling so cold in fact that all the fuel introduced into the cylinder may not burn (known as wet stacking) this fuel will bypass the rings and dilute your oil, obviously very bad for a brand new engine!
2.Don't run the engine hard for the first 100 miles, run the engine in it's sweet spot (torque peak) 1600-1800RPM.

1.Do check all fluid levels, remember humans built the machines that built these vehicles. Humans perform some assembly on these vehicles and humans make mistakes. Nothing worse than breaking in a new vehicle that's low on lube or overheats at the first sign of a hill due to low coolant!
2.DO very engine RPM's and speed as much as possible in the first 100 miles, try to put the first 100 miles on all at once (i.e. No 5 mile trips to work or 7-11). After the first 100 miles drive the vehicle like you own it.
3.Do change your oil at 500 miles, get that assembly lube and break-in materials out of the engine. You may also opt to change your rear end fluid to get the initial break-in material out of it as well.
4.Do put a load on the engine at 500 miles, and work it! Diesels are designed to work, pulling a nice load will help your engine components mate to each other. With an additional 10,000 or so miles of normal use your engine should be broken in.