JP>        Let me dig into my aviation experience to reply to this. I
JP>  do not think that you would get any more mileage using the high
JP>  octane fuel. The higher octane rating is only for "pedal to the
JP>  floor" neccessity. My Explorer with a high compression V6 is
JP>  quoted in the manual as needing the higher octane fuel. I never
JP>  got it in the tank. I drive very conservatively and can not
JP>  remember ever flooring the pedal where the full power output
JP>  would be called for. These higher octane fuels have more knocking
JP>  retardant chemical in them to prevent this damage to an engine,
JP>  on the long run. I doubt that having seen you drive, that you
JP>  use more than 50% of available MAP thus, you do not need this
JP>  higher octane fuel. I doubt that there is more humph in the
JP>  dearer fuel that would give you more m/g at a lesser butterfly
JP>  opening if there is still a butterfly to open in the new carbs.

JP>        Let us see what others would have to say.

 That is Right on Jean. There is NO magic "Miledge  Indegerdent" in the
 higher Octane fuels other the the ability to retard knocking on Heavy
 loading of the engine.  Now of course for those engines designed for
 the highest octane avaialble when fueled with the lowest grade may
 activate the Knock Sensor Retard circuit and that Will gove Reduced
 miledge .Btu for the Lower Octane cars you WILL NOT get higher miledge
 by paying more for the higher octane fuel. Unless of course the
 lightening of the Wallet significantly reduces the load the car has to
 carry.
---
 þ SLMR 2.1a þ This note from El Cajon California USA