Debunking Fuel Myths
The next time you fill up at the pump, you'll want to make sure that you don't fall for these myths. Save money, time and pointless worrying: These are common anecdotes we've heard from readers and our old-school, leaded-fuel-breathing elders.
Myth: Using premium gas will make my car perform better.
You're not going to do any good by filling up with premium gas if your car's manufacturer doesn't require or recommend it. There are rare instances where you may want to consider filling up with premium, but for the most part, today's computer-controlled vehicles can adjust an engine's performance in the majority of conditions. Some people may report pinging or knocking under heavy engine strain when towing or carrying a full load of people up hills. Modern knock sensors typically detect this pinging before you hear it, but if you do hear it, filling up with premium can help resolve it.
Myth: It's better to fill up in the morning or at night because you'll get more fuel.
We've heard this one for years. The reasoning is when the fuel is cooler, it's denser. A denser fuel will pack more energy in the same amount of space, so you'll get more bang for your buck. While density may change with temperature, underground storage tanks sit 15 to 20 feet below the surface so the fuel stays around 55 degrees Fahrenheit. One of the only times that you'll find a warmer, less-dense gas is if the fuel doesn't have time to cool off after being pumped into the underground tanks. Fuel temperature stabilizes quickly, so the chances of this making any difference are slim.
Myth: It's OK to top off your gas tank after the nozzle automatically shuts off.
Those few extra pumps after the nozzle automatically shuts off aren't worth the trouble, especially considering the fuel may just be rerouted into the station's storage tanks in some areas, according to the Environmental Protection Agency. You may also harm your vehicle's evaporative control system that prevents fuel vapors from escaping into the atmosphere. This system is designed to re-burn vapors, not liquid gasoline, that get pushed out of the gas tank when you fill up.
Myth: Pressing the fuel nozzle halfway will make you pay for gas you don't get.
This is a relatively new myth to us. And it is a myth. Dispensers have volumetric measures that can gauge whether they're pumping fuel slow or fast. It's not an on or off nozzle that can only accurately detect when the pump is going full bore. High-volume stations have their metering devices tested for accuracy by state and local regulatory agencies.
Myth: Using the wrong octane fuel will void my warranty.
It's not likely, but we wouldn't rule it out. Some automakers claim damage can be done to their vehicles' engines with prolonged use of the wrong octane gas. That's why we recommend carefully reading your owner's manual. Yes, it's big and intimidating, but there's a lot of valuable information within it. Will you likely void your warranty because you fill up with regular one time? No. Automakers that require premium acknowledge that a lower octane can be used in an emergency situation, but premium is strongly preferred.