While tripping merrily through the mail, Landon Robinson was overheard
 
 WL> 2. That higher octane gasoline is cleaner or provides
 WL> any other benefit in engines that were designed
 WL> to run on lower octane.
 LR> I've none for some time that this was bogus advertising, the only
 LR> thing that higher octane gas does is it keeps high compression (or
 LR> highly timed) engine from pinging. Had a car a couple years ago that
 LR> would ping on anything other than 92 octane when ever you floored the
 LR> gas pedal. 
I was chatting with a gasoline wholesaler today (I sell to the oil trade),
and he mentioned that using gas with too high an octane for the engine can
actually result in unburned fuel coming out the exhaust (the higher the
octane, the slower and more even the "burn" and you may not have time to 
burn all the fuel before the exhaust valve opens).
Don
... Fharhfegnookie: Fun in the back seat of a Volkswagen.
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