As far as car tips go, there’s one that we seem to hear every winter, and that’s to never let your gas tank dip below a quarter full, lest the gas lines freeze. But is that true? Can that really happen?

Most landlords require their tenants to keep the heat on at a certain temperature to avoid the water pipes freezing, but does the same logic ring true for cars? If not, are there other reasons to keep your car’s tank a little more full?

We've always been told to keep our cars' gas
tanks fuller than a quarter during the winter to
avoid gas-line freezing, but is that entirely necessary?

While it stands to reason that keeping your gas tank more full would be the safer option in terms of not running out of gas, we’ve often wondered if there’s any truth to the idea that keeping a fuller gas tank will prevent gas lines from freezing. In the past, drivers have been advised to add products like Heet to their gas tanks during the winter to absorb the moisture/water that can get into a gas tank and freeze it. Now, however, thanks to better-engineered cars and better gasoline, fuel-line freeze-up may be a thing of the past. Since today’s gas contains ethanol, a built-in anti-freezing agent, worries about water in gasoline have all but disappeared. Similarly, concern over condensation has decreased, since modern fuel injection systems are better sealed and have almost no exposure to air.

But aside from keeping your gas tank at least a quarter full to prevent potential freezing (though highly unlikely, it probably could still happen), more frequent fill-ups can help keep your fuel tank cleaner. Some fuel tanks have filters to sift through things like rust particles and fuel sediment, but running low on gas too frequently may choke the filter if you do so too often.

In general, it’s best to keep a safe amount of gas in your car at all times, but the amount varies based on your lifestyle. If you tend to get stuck in highway traffic frequently, it’s not a good idea to let the tank run low, since you might run out of gas. If you live in warmer climates where gas-line-freezing isn’t an issue, don’t worry about keeping a certain level of gas to stave off the cold.