On 6/5 we (my wife and I) bought a 2wd 3500 CC D(LLY)/A. I live in Charlotte NC. We bought the truck in Montgomery, Alabama. The salesman told me their was really no "break in" period, so just drive it. I did keep it between 45 and 60 mph for the first 200 miles. It was a 500 mile trip. After 200 miles I started to speed up in 5 mph increments for 75 to 100 mile and was driving it at 70+ mph after 400 miles. Should I worry? I thought the break in period was to properly wear the bearings in, and that the rings/cylinders are not a big concern anymore because the rings rotate on the pistons now, and the new materials of the engine internals are close to the same hardness. Is this true. The Duramax supplement to the owners manual doesn't say anything about a break in period, but the manual does. I didn't see it in the manual until after I got home. The salesman said to change the fuel filter at half of what GM recommends. How often should the fuel filter be changed? I figure on changing the engine oil/filter every 7K. I have put 2k on the truck in two weeks. My mileage went from 16.4mpg to 19.4mpg (mostly highway at 70+) on the last tank. Its getting better. This thing hauls ass. My last truck was a 2500hd 6.0l CC with 4.10's. It was a good truck, but we go to the keys twice a year and gas is a killer. With the travel trailer and kids it will be pulling an 8000 lb load. I will be making my first trip to Florida with the trailer in July. Thanks for any input and we I really like this truck. My 12 year old son loves it also, he likes hearing the turbo whine as we pass Fords.





Scott

Everyone has their opinions about engine break in. Some say that a good break in by varying your speed and throttle will help seat the piston rings better. My cousin has a 97 1/2 ton with 160K on it and has never burned an ounce of oil and he did absolutely no break in procedure with it. But im sure you could find someone else with a personal story that completely contradicts this. I picked up my truck about 200 miles from where I live just to be on the safe side a pulled off the interstate a few times on my way back to vary my speed a little but otherwise stayed on the interstate the whole way doing about 70-75. If you havent changed the oil yet I would do that as soon as possible I have about 600 miles now and I changed the oil at about 400 miles. Then every 5-7k should be plenty. Im planning on changing fuel filter and allison filter sometime soon before 1000 miles.

and oh yeah you gotta love that turbo...sounds like a jet taking off

Bart,


Congrats and welcome to the forum...http://www.dieselplace.com/forum/smileys/Clap.gif


I'm one of those who firmly believe in a break in period, although most of my experience with engines has nothing to do with Duramax diesels.


Biggest reason for the speed restriction on your truck is the rear end needs to get broke in and it'll create quite a bit of heat doing that. Enough to blister the paint on the housing if pushed too hard or the clearances are a bit tight.


They also list a speed restriction for the first 500 miles of towing for the same reason. Some say it's not necessary, but it's in the manual so I figure it can't hurt.


And speaking of the rear end, make sure you check the fluid level in the differential. Most trucks have been coming from the factory with about 2 quarts in them instead of the nearly 4 quarts it's supposed to have in it. Pull the rear plug and the oil should be with in 1/2 inch of that hole.


You may want to consider changing that differential and engine oil right now. A lot of the guys are finding quite a bit of crud in the differentials from the break in process. Also, there is always a little crud left in the engines from the manufacturing process and intial break in wear on the components. Don't forget your Ally filter either, maybe include it with the other stuff now...http://www.dieselplace.com/forum/smileys/Ermm.gif