Does It Matter? (Gasolines)

My Dad would go out of his way to save a few cents on a tank of gas.  He watched station prices closely, and filled up wherever it was cheapest.  When I was a teenager, I found a ledger sheet under the front seat of his car filled with odometer readings (to the tenth), gallons (to the tenth), intervals, and his mileage calculations.  This was before we had pocket calculators: he did long division, sitting at the pumps, I guess.  He didn't just check a new car against the manufacturer's claims, he tracked it for months.  He compared alternative commuting routes.  He hated waste--especially wasting money.  It annoyed him that he had nothing to show for buying a tank of gas other than getting around.

I, on the other hand, am a brand loyalist and will go out of my way to refill the tank with what I "always" run.  I can't prove it, but believe that my cars "don't like to be surprised" by a change in additive formulation.  I also believe, absent evidence, that the refinery chains filter their gas more carefully up to and including the station pumps.  Years ago I persuaded myself that Amoco's advertising was true: that it had superior detergents.  Amoco became BP.  Never had a problem.  If it ain't broke, don't fix it.  I plan road trips around BP station stops.

But I got into an email exchange about this with my Porschephile pal recently.  "Don't you realize that BP is 15% ethanol, which is bad for injectors?"  Yes, I knew BP had ethanol, and no, I didn't know it was hard on fuel injectors.  I thought ethanol was good: it tends to retard gasoline deterioration, to reduce carbon build-up, and to burn cleaner than gasoline.  But "bad" makes sense if you think about it: gasoline is more lubricious than ethanol (fuel injectors have moving parts), and ethanol can have a corrosive effect on fuel system parts, including aluminum, but especially some plastics.  Maybe my affection for BP amounts to piling inference on top of inference, on top of misoverestimated decades-old advertising.

My Porschephile pal went on to point out that ethanol has about 85% the energy release of gasoline.  BP contains up to 15% ethanol (some other brands stop at 10%).  15% less energy from 15% ethanol is 2% less bang-for-the-buck than 100% gasoline.  I am perfectly happy to emit 2% more CO2 if I can get 2% more power and gas mileage.  But how would I know?  I can't feel 2% more power under hard acceleration, and my mileage calculations get rounded to the nearest whole gallon (when I bother to do them).  Still, if my injectors are 15% happier, I'm happier.  Inference on top of inference again...  

He runs Shell in his classic Porsches, having done some comparative research on brands.  He says the best way to know what you are buying is to check the pumps at your station.  Ethanol percentages change from state to state, city to city, even within brands.  My local BP station's pumps say "up to 15%."  My local Shell station's pumps say nothing about ethanol.  So, as of my most recent tankful, I "always" run Shell.

Things that make you go "hmmmmmmm."  (The Stuck/Ludwig/Bell Porsche 962C came 2nd at LeMans in 1988.)