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Path: utzoo!linus!philabs!seismo!harpo!eagle!mhuxl!houxm!ihnp4!ihu1f!dave
From: dave@ihu1f.UUCP
Newsgroups: net.auto
Subject: gas mileage
Message-ID: <210@ihu1f.UUCP>
Date: Mon, 7-Nov-83 13:55:01 EST
Article-I.D.: ihu1f.210
Posted: Mon Nov  7 13:55:01 1983
Date-Received: Tue, 8-Nov-83 13:14:08 EST
Organization: AT&T Bell Labs, Naperville, Il
Lines: 26


  I have carefully monitored gas mileage for 5 years.  The best gas
  for mileage that I have found is actually a mixture.

  Here is what I have found:

    1.  Too low of an octane will cause pre-ignition detonation
        (combustion chamber "knock") before the power stroke is over.
        The result is less mileage/gallon.

    2.  Too high of an octane will not knock, but will not finish
        burning in the combustion chamber before the exhaust valve
        opens.  The result is less mileage/gallon.

  Therefore, to maximize gas mileage, you must find an octane
  combination and engine timing that will knock only under heavy
  accelerations.  When an engine occasionally knocks a little, you
  are getting the best mileage.

  The mix that I find works the best is when your tank is half full,
  first fill it with Shell 89 octane.  Next time, fill it with Texaco
  91 octane.  Watch out for ethanol in Texaco, your car won't start
  when it is below 20 degrees.

  Finally, for 5 years, my gas mileage always goes down in the
  winter, not because of the choke, but because of the de-icer
  additives in the gas.