GMan and Andras,
Okay this is enough!<g>
I can understand where both of you get your opinions regarding oil changes, and you both make good points. However, Andras is pointing out some very interesting facts. Where do those contaminants go? As for all the automobile manufacturer recommending 10K mile intervals; first of all they would like to sell you another vehicle and soon, secondly, they were recommending 7,500 mile intervals back when G-Man was agreeing that 3,000 was a good thing.
I drive 60,000 miles a year mostly in Mercedes, a gas and a diesel. The diesel went 380,000 miles before the first engine overhaul. I know this is not scientific statistical analysis, but it must mean something. This 380,000 miles had the following admittedly FANATICAL oil change interval/method:
3,000 mile intervals
Chevron DELO 15W40 multigrade(truckers oil)
preferable drain time, Friday night
Pull the plug as soon as possible after killing engine(engine as hot as possible)
Drain at least over night, maybe 'til Sunday
Change filter every time
Replace plug, fill filter housing
Crank engine and log in book
If you don't have facilities to take such fanatical measures, go to the JiffyLube, but go there when your engine is at operating temperature.
Draining the oil from a cold engine, leaves the vast majority of the contaminants "stuck" to the parts inside the engine.
Good luck and keep changing that oil.
I hope none of the beginning comments insulted anyone, they were in fun.
PS Even though I'm in Texas I'm not a salesmen for an Oil Company.