As a winter storm approaches, drivers often hear the same advice: Fill up the car while it’s cold. Keep your tank half full. Pump slowly to avoid wasting fuel.
But how much of that advice actually saves you money – and how much is just a myth?
While winter weather affects driving conditions and fuel consumption, many popular gas-saving tips resurface during a storm despite having less impact at the pump.
Is it better to pump gas in cold?
You may have heard this tip before: Fill up your tank when it’s cold because you’ll get more fuel for your buck. Gasoline expands and contracts with the weather, so when it’s cold outside, the fuel is denser and you get more bang for your buck.
Although this is scientifically accurate – temperature affects the density of gasoline – here’s the problem: The fuel you pump doesn’t freeze like you do in the cold. It is stored in underground tanks where the temperature barely varies throughout the year, usually around 50 degrees.
According to a study conducted by Consumer Reports, even if your local gas station has subjected its vast reserves of fuel to the elements, the change in temperature has a minimal effect on the volume – a difference of only a few cents.
If the temperature doesn’t change, nor does the density, and if you only pump gas when it’s cold you may get unnecessarily cold. Whether morning or night, summer or winter, the temperature – and density – of the fuel is essentially the same.
What should drivers do during a winter storm?
Some people fill the gas tank when it is half empty. Maybe it’s habit, or maybe it’s due to range anxiety, even in a gas-powered car.
Other rumors have surfaced that it is economically sound to fill the tank half full to prevent splashing and evaporation (and therefore wasting) of gasoline.
But, according to Adrienne Woodland, a spokesperson for AAA of Michigan, it’s good practice to fill up to about half the tank, especially during winter storms or when temperatures drop.
“We recommend drivers, especially during the winter, keep your tank about half full,” Woodland said. This advice is for safety in an emergency, not for superstition or concern about gasoline evaporation.
Driving on empty is also not good for the longevity of your car.
Inside the gas tank is a small mechanism called a fuel pump. The fuel pump is responsible for moving gasoline from the tank through the fuel lines and into the engine where it is combusted and converted into horsepower. The fuel pump relies on a constant stream of gasoline to move through it, which lubricates the pump and bearings and keeps it cool.
If you are running on fumes, this can cause the fuel pump to dry out and overheat. It costs more than a couple of tanks of gas to replace it.
If you run out of gas in an emergency, don’t worry. But regularly driving your car until the fuel light comes on is probably a bad idea. For that reason – not because of evaporation or range concerns – it’s generally a good idea to fill up when you get down to a quarter of the way in the tank to make sure you’re not putting any extra stress on your fuel pump.
Other ways to keep gas for a long time
AAA’s Woodland said there are some concrete methods of fuel conservation that don’t involve myths and urban legends.
Woodland said mixing tasks, paying in cash and avoiding aggressive acceleration are all proven ways to make gas last longer.
This article originally appeared on the Detroit Free Press: A winter storm is coming. Why does it matter when you fill up with gas
Reporting by Liam Rappleye and Joe Jacquez, USA TODAY/Detroit Free Press
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