Why you should keep at least half a tank of gas in your car during winter

If you’ve ever worried about whether the gas in your car will freeze in the winter, fear not. But it’s not a bad idea to keep the tank at least half full when the temperature dips below zero.

Scientist says the gas won't freeze, but if condensation forms in your tank, the water will

To be on the safe side, science suggests it's best not to let the gas tank get too low during the winter months. (CBC)

If you've ever worried about whether the gas in your car will freeze in the winter, fear not.

But it's not a bad idea to keep the tank at least half full when the temperature dips below zero, says Michael Edwards, director of strategic initiatives at Science East in Fredericton.

The water will freeze, and then you get ice crystals that can get into the fuel line and it will slow the flow and your car will sputter, or worse you can even block the fuel line.- Michael Edwards

Because gasoline is a mixture of chemicals, it would never really turn into a solid, he said. But at around –50 C, it might get "a little syrupy." (Fun fact: the same things happens with dish soap, he said.)

Water, on the other hand, will freeze much quicker.

And water can get into your tank through condensation — the same way it can get on your bedroom windows, Edwards said.

If you have have only a small amount of gas in your tank, then there's lots of room for air above it. If that air is warmer than the cold walls of the gas tank, Edwards said, it can lead to condensation, and water running down the walls of the tank into the gas.

"And that's not good because the water will freeze, and then you get ice crystals that can get into the fuel line and it will slow the flow and your car will sputter, or worse you can even block the fuel line," he said on CBC's Shift.

If that does happen, Edwards said a fuel additive containing methanol — which freezes at a very low temperature — sold at automotive stores can usually solve the problem.

With files from Shift