Gasoline mileage

Doyt W. Echelberger Doyt at
Sat Aug 31 09:13:07 EDT 2002

Posts by other listers in other years have indicated that their mileage was
best when they used the higher octanes.  I never ran any mileage tests, but
I can detect a harsher sound to my exhaust at idle when I run a middle
octane fuel for some when 93 is not available and I am near
empty on a trip somewhere.

Last year when fuel prices skyrocketed, I tried running the fuel level down
to near empty and then put in 5 gallons of 89 octane (mid grade) and I
could detect a slightly different sound to the engine.  I did the same test
with 87 octane (regular) and the harshness was more pronounced.  My engine
even runs different on 92 octane (which may be just my imagination), when I
can't get 93.

Sunoco sells a 94 octane here in Ohio.....very costly.  I've tried it and
my engine doesn't seem to distinguish between the 94 and the 93.

My 87 5ktq has an ECU that has been modified to advance the stock ignition
settings across the entire RPM spectrum, so that might the reason that my
engine is unusually sensitive to octane ratings.

Also, 93 octane is achieved differently by competing brands. Different
additives result in the same octane number.

I try to avoid gasolines that achieve their high octane number by using
ethanol. Some of them have up to 10% ethanol, and I find that any ethanol
is too much and results in a multitude of engine operating problems for my car.

I encounter the ethanol gasolines in large cities where aggressive
pollution control is mandated by EPA regulations.  In Ohio it is required
to have a label on the pump that indicates such, if the fuel being
dispensed contains ethanol.  Ethanol laced fuel is also found in farming
communities at Co-ops.

In Ohio, Marathon stations sell only real gasoline, with no ethanol,
ever.... (according to my trusted Marathon station owner in Parma.)

Doyt Echelberger
87 5ktq  in Ohio  USA

At 12:18 AM 8/31/2002 -0400, you wrote:
>What might one expect to get as reasonable gas mileage on '89 Audi
>200 Turbo if I buy the higher octane gasoline?
>Speaking of gasoline, is there a difference in brands and/or
>stations, or is 93 the exact same everywhere ???   Fay

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