Condensation in your fuel tank is never a good thing. It makes it harder for your car to start and causes rust in your gas tank, among other things. Here's how to reduce condensation in your fuel tank.
Know why condensation occurs in gas tanks. Just like when you pull a soda from the refrigerator, a gas tank will eventually be covered in condensation because of the temperature change. Driving along a hot asphalt road creates friction between your car and the pavement. This heat transfers to your fuel tank, where it mixes with the colder gasoline and creates condensation inside of your tank. It will build up on any available surface and eventually, the condensation will form droplets and fall into your gasoline.
Limit the amount of air in the tank. Air has a certain amount of water vapor in it. So if you can limit the amount of air in your fuel tank, you can limit the amount of water vapor and effectively, the amount of condensation in your fuel tank. This is easily accomplished by keeping your fuel tank full or nearly full of fuel. Never let your car get below half a tank, if not three-quarters of a tank full. Fill up frequently to avoid letting the fuel in your tank run low. Doing so will reduce the amount of surface area on the inside of your gas tank on which condensation can develop. This is an especially effective trick when it's humid outside, or when you're expecting a drastic change in temperature, as a full tank will prevent vapors and condensation during this type of weather.
Understand that condensation isn't as much of a problem as it used to be. Years ago, gasoline didn't contain as much ethanol. Today, fuel is usually mixed with at least 10% ethanol and this tends to mix well with water. So even when small amounts of condensation appear in your fuel tank, the ethanol helps to carry the moisture to your engine where it will be vaporized or burned up.
Try using a fuel additive. If you can't find gasoline that contains at least some percentage of ethanol, then purchase a fuel additive from your local automotive store. Pure gasoline is lighter than water, and will float on top of water or condensation instead of mixing with it. If this happens in your gas tank, consider the amount of condensation build up that could possibly be sitting at the bottom of your gas tank, rusting it away. A quick and simple fix to this problem is to use a fuel additive every time you fill up your car with pure gasoline. Following the directions on the container, pour this directly into your fuel tank. When mixed together with pure gasoline, this will serve the same purpose as ethanol, and reduce the overall effects of condensation in fuel tanks. No need to be concerned about your gas tank rusting out from fuel tank condensation if you're using fuel that contains water-soluble elements like ethanol or fuel additives.