Pay attention to your gas mileage!

Writer:  Ron Knight (Chemist)

I used to live near a convenience store that is owned by a friend of mine and I bought most of my gasoline there.  My Ford F-150 got 19+ mile per gallon in town and my wife’s Subaru got around 30 miles per gallon.

We moved a few weeks ago.  There is a convenience store that is 2 miles from my new home and 2 miles from my office so I started getting gas there.  After a couple of weeks of buying their gas, I noticed that neither vehicle was getting as many miles per tank of gasoline as they were when I used gasoline from my friends store so I checked the fuel mileage.  My F-150 was getting 16.3 mpg and the Subaru was getting about 26.5 mph.  These numbers represent a mpg decrease of 14.2% for the F-150 and a 11.7% decrease for the Subaru.

I took a 1.25-gallon container to the store and bought a gallon of their regular gas.  I brought the gasoline back to my lab and ran a simple 30-minute test on the fuel and the results were so far off of what I expected that I was not sure what I had purchased.  I started over and run a more complex series of tests.

After 2.5 hours this is what I found:  Even though the dispenser has a “sticker” on it saying that the fuel may contain up to 10% ethanol, the fuel that I analyzed contained 12% ethanol.  After I removed the ethanol, only gasoline remained.  When I analyzed this gasoline it was “Grade C” gasoline with no additives.  (Did you know that there are 3 grades of regular gasoline?  Grades A, B, and C).  I ran the same tests on my friend’s regular gasoline and it was Grade A and contained 5% ethanol.

If I drive 12,000/ year in my F-150 consider this:  I would use about 632 gallons of my friend’s fuel and 736 gallons of the new store’s fuel.  That is a difference of 104 gallons of gas per year (or about $200/year).  As long as my friend’s fuel was no more than $0.32 higher than the new convenient store’s gas price, I would save money!  How many times have you seen the price of regular gas vary $0.32 per gallon?  I have also read several articles that state that unless it is a “flex fuel” engine, any quantities of ethanol greater than 10% is detrimental to the life of the engine.

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