Automotive Myths

We’re not sure where some of these car myths started. Things like mixing low- and high-octane gas to get an octane level higher than high—that had to be a contest between Dumb and Dumber. The campfire-story genesis doesn’t seem appropriate either, because some myths are actually based in fact, maybe old facts, but facts nonetheless. We’ll start with that old grudge move: Sugar in the gas tank.

Not So Sweet
Sugar in the gas tank will blow it up. The jerk who thought this one up assumed the sugar would melt, ooze into every nook and cranny of the engine and solidify once the engine was turned off and cooled down. Think giant candy mold. Wrong.


Back in 1994, researchers at Berkeley figured out sugar doesn’t dissolve in gasoline. Oops. Sugar in the gas tank can play havoc with your fuel filter or require the gas tank be pulled and cleaned, but destroy the engine. Nope.

Coming Out of the Closet?
Mothballs increase octane. Believe it or not, this was once true. During World War II, naphthalene was the active ingredient in mothballs and octane ratings of gasoline were 60 to 80. Since naphthalene’s blending motor octane number is 90, mothballs could increase the fuel’s octane rating.


Today, though, modern mothballs contain para-dichlorobenzene (try saying that five times fast!) rather than naphthalene, but the latter is making a comeback due to toxicity concerns of the former. But considering the higher octane levels of today’s gasoline and the fact that naphthalene has a high melting point and can block jets and filters, mothballs are best kept in the closet.

What Kind of Fuel Am I?
Does mixing low- and high-octane gasoline result in higher octane than the high octane alone? If you want to test this yourself, be sure you add one when the gas tank is half full of the other. Trying to fuel up with half of each in an empty tank could result in a pocket of pure low or pure high fuel surging through the system. The two fuels have different density levels and may not mix immediately.


Don’t bother, however, because you won’t get a higher octane even with a well-mixed blend. It’s simple math: half a tank of 87 plus half of 91 equals 89 octane. Mixing leaded high and unleaded high is equally useless.

Juice Masters
Storing a battery on the ground or on concrete will discharge it prematurely. Like the mothball myth, this was once true. At one time battery cases were made from natural rubber and would discharge more quickly depending on where they were stored.


Today the cases are made of polypropylene or other modern materials that allow them to be stored anywhere with no difference in the normal rate of discharge. Of course, if you leave a battery stored long enough anywhere—even in the car—it will discharge.