I work as an emt for a private ambulance company before I start my shifts I usually check the oil, ok heres the wierd part on our ford ambulances i'll check the oil and even with about 3000 miles on the oil, they get changed every 3000 the oil and yes it is on the dipstick but it is almost clear, but this is on our 6.0 powerstrokes our chevys have black oil, what gives? I know this is wierd.