My
thanks to the American Automobile Association (AAA), though the gratitude can
only be described as belated. They just
released a research study which found that American motorists are—and have been
for decades—wasting over two billion dollars annually by buying premium gasoline
for vehicles that don’t require it.
Exactly
who’s to blame for this thoughtlessness is hard to figure out. A part goes to service station managers who,
as I recall from the past, suggested that filling up with their higher priced
gas was “better for my car.” Add to the
list of culprits whoever issues auto drivers’ handbooks. My 2004 6-cylinder Jaguar instructions read:
“The preferred fuel should have an octane rating of at least 95, though some
countries have only 91 octane.” Even my
modest 2012 4-cylinder Nissan Altima booklet states: “Use unleaded gasoline
with a Research octane number at least 91.”
And then, of course, whoever named the higher octane fuel “premium,”—probably
a PR exec in the petroleum industry—kicked it off by making it sound as though
it’s in some way superior.
Quite
simply, premium gas is normally 91
octane, whereas midgrade is 89 and
regular is 87. The only difference
relates to the combustion speed, with the higher the octane rating, the slower
it burns. As all are now unleaded,
pollution is no longer a factor. Base
your decision on which to use solely by performance. In
the 1950s and 1960s, when auto engines carried higher compression ratios,
slower burning helped prevent engine "knock." Because of the lower compression ratios of
today's cars, most function satisfactorily on the 87-octane fuel. The test is simple to conduct. With the lower octane gas in your tank,
accelerate up a slight grade in drive gear.
If you experience no unrelenting "pinging" of the engine, then
save yourself the cost of the more expensive fuel. And just so you’ll know, my two vehicles
function well on the cheaper 87 octane fuel.
I’ll bet for most of you it will be the same.
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If you enjoy this weekly Straight Talk by Al Jacobs, you’re invited to check out my monthly Financial Newsletter, as well as my new book, The Road to Prosperity
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