RE: oil change interval!!!
First off, an oil change is only $40 if you do it yourself. I can't speak for everyone here, but for those of us who bought an '06 it's possible the truck has been sitting on the lot for about a year. In that case, you'll want to change the oil earlier than scheduled. I've also heard reports of extremely dirty oil at 3500 miles due to engine break in and the age of the oil. It can't hurt, and $40 is a small investment to keep everything running well.