one more little bit to add to my diatribe:     :)

consider this:   most people drive about 15,000 miles per year.
                 if you change the oil every 7,500 miles, that means you
                 replace the most critical component of your engine only
                 EVERY SIX MONTHS.

do you REALLY want to spend that much on a car and not even look under the
"hood" for six months???  that's really putting a lot of faith into the
workmanship of the product and the last mechanic and those parts you bought
at the local Bubba's Bumper Benders.

a bus can get awfully lonely in six months ... and they tend to get kindy
persnickity if you don't pay attention to them. :)

joel