What is the best way to break in my new 2005 GMC 2500HD DUramax. I will be driving 15 miles each way to work daily and towing about 20% of my total driving time. I normally put about 10,000 miles on unit annually. I bought this looking for a 200,000 mile dependable vehicle.
Also I just rec'd my 2005 trailer and we would like to take a shake down trip in about 2 1/2 to 3 weeks. By then i should have about 350-500 miles on unit. I live in So. Cal and there is the grapevine. My trailer is rated at 8000 so it is no where near the peak that this vehicle can haul. SHould pull it like it wasn't there. We will probably only be going 2-3 hours away on first trip. Will this be a problem and what do you recommend for break in and the first couple of thousand miles to make it break in well.
Also what additives would you use I am considering Stanadyne Performance Formula. Any recommendations are appreciated. Also should this go in every tank? And right from the intial tank or should I wait a bit before starting additives?
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Thanks
Bob

Well you shouldn't haul anything until you have atleast a 1000 miles on it and no constant steady speeds during this time then after that its done breakin is over..

Every new car, and the dmax, I have ever bought I used the same break in method.

1-200 miles up to or at or about 45. No hard acceleration.

2-400 miles up to 55 but don't hold for long. Slow but firm acceration.

4-500 miles up to 65 but don't hold for long, and accelerate up to 70 and back off every once in a while. Normal acceleration.

After 500 drive it as you normally would.

I have NEVER had a new car I broke in this way use any oil, "0" period.

I have sold these cars with over 100K on them an they all lasted to 200K, or they wrecked it and still didn't use oil.

Most people don't want to do it slow, but it has been very successful for me.

As outlined in your owners manual


New Vehicle Break-In



Notice: Your vehicle does not need an elaborate break-in. But it will perform better in the long run if you follow these guidelines: <TABLE border=0><TBODY><TR><TD vAlign=top> • </TD><TD vAlign=top>Keep your speed at 55 mph (88 km/h) or less for the first 500 miles (805 km). </TD></TR></TBODY></TABLE>
<TABLE border=0><TBODY><TR><TD vAlign=top> • </TD><TD vAlign=top>Do not drive at any one speed, fast or slow, for the first 500 miles (805 km). Do not make full-throttle starts. </TD></TR></TBODY></TABLE>
<TABLE border=0><TBODY><TR><TD vAlign=top> • </TD><TD vAlign=top>Avoid making hard stops for the first 200 miles (322 km) or so. During this time your new brake linings are not yet broken in. Hard stops with new linings can mean premature wear and earlier replacement. Follow this breaking-in guideline every time you get new brake linings. </TD></TR></TBODY></TABLE>
<TABLE border=0><TBODY><TR><TD vAlign=top> • </TD><TD vAlign=top>Do not tow a trailer during break-in. See Towing a Trailer (http://service.gm.com/servlets/CellHandler?CellId=74100&RefDoc=816891&evc=sm) for more information. </TD></TR></TBODY></TABLE>

Cobra is right,

The "touchy" 500 miles is what I've used on all diesel trucks since first one. No-oil consumption, no-injector failures, no-blown head gaskets, no-warped rotors.

All have started towing at roughly 500-600 miles, and are still towing for those that have bought the used ones from me (a few are towing much heavier than I would ever considered doing, and have had "brakes" problems, but that's another story).

Break-in on a diesel (lower RPM's, heavier pistons and skirted sleeves, etc.) may not happen for quite a few miles (some settled down at 30K, others at 50K), but the instructions in the GM manual have been good by me, but I don't enter my trucks in any races, especially when towing.

RF