crf450

Guys what are your thoughts, for years I did the 3000 mile oil change,then about when electronic fuel injection hit engines started lasting longer. I own a company with seven trucks and ran 3 chevy pickups 360,000 to 420,000 miles all on 10,000 oil changes and sold them all still running, two not burning oil yet. I had the same luck with ford 150 pickups, and have 3 dodge cummins pickups that I change every 15,000 miles, I have 485,000 miles on the 03 model 305,000 on a 05 model and 240,000 on a 07 model, none burn any oil. All the trucks I own pull trailers 1/2 the time and work hard. I have a 07 accord that recomends oil changes every 8500 miles, and I have my favorite the 370z that recomends every 6000 miles. The oil I am putting in it recomends changing every 15,000 miles and I compromised at 10,000 and at ten it still looks good and is still on full.
Do you guys think we have all been suckered into buying twice the oil we really need to ?? I have read some tests that say used oil still performs way better than is needed to protect the engines, read things that say oil is way better than it used to be etc. My expirience tells me I am taking very good care of my cars and trucks. What do you guys think ????
I do love my z and run it hard, I am a speed freak and have access to an old runway where I eat camerros and mustangs and even some vetts for lunch, these guys don't know how to hook up! I have hit 170 mph and am thinking about supercharging. My best races have been ontracks with nsx's. I do moniter and take very good care of my cars but use them like they should be used.