what some folks have explained to me is that sometimes (oh, yeah?) the
higher octane will have a "cleansing" effect on the injectors and the
back of the valves, so the engine gets cleaner as you drive ... resulting
in better use of the fuel. so you get better mpg.   eh?

all i know is that, for MY bus, with MY style of driving, and using the
gasolines in MY area, the 93 octane down here don't make a poot's worth
of difference from the 87 octane. it just costs more.

so why do i still dump a tank of 93 in every now and then??
old habits die hard ... and besides, it can't HURT, right? ;)

joel