You’ve probably heard that you should keep your gas tank full in the winter because gasoline freezes when it gets extremely cold. Strictly speaking that is true. Gasoline freezes at -100oF. However, you don’t have to worry about those extreme temperatures in New Jersey. While diesel does have a higher freezing point, winter diesel blends are sold to minimize the risk of the fuel freezing.
Even though gasoline isn’t likely to freeze in your gas tank, you still need to keep a significant amount of gasoline in your tank to prevent other problems. So, while the reasons for keeping your tank topped off in New Jersey weather are faulty, the advice is extremely sound.
Gasoline itself doesn’t freeze, but condensation or water vapor can get into the tank and freeze. This isn’t good because water isn’t supposed to be in your gas tank to begin with, but occasionally it does happen. When water gets into your gas tank, the alcohol in the gasoline absorbs it. If the ratio of water to alcohol is more than your car can handle, the water will cause havoc.
Another problem you may experience, if there isn’t enough gasoline in your tank to prevent it, is gasoline separation. When gasoline separates, the heavier molecules fall to the bottom. This can also be caused by too much water entering the gas tank.
You should also keep your tank above half full because keeping it lower than that could shorten the life of the fuel pump. Then, there’s the possibility that your fuel gauge isn’t accurate, leaving you with less gas in your tank than you thought. This means you may be very low on gas or have a different problem you do not even know exists yet.
It’s safer to keep your tank more than half full, so that you lessen the risk of getting one of these unwelcome surprises.