Image by Phillie Casablanca via Flickr

Reducing condensation in a car’s fuel tank really deals with two problems. The first is the condensation. The second is the water that the condensation puts into the fuel in the tank. If you solve the first problem, the second one will go away. You will never eliminate all condensation within a fuel tank, but you can reduce to the level of being of no consequence to your car’s performance.

Condensation forms in a fuel tank from the same principle as condensation on the outside of a cold drink.

When warm air meets a cool surface, condensation forms. Your gas tank warms up above the ambient air temperature when you drive or if your car is parked over hot asphalt. The tank gasoline in the tank also warms up. Liquid does not cool as rapidly as air. The outside temperature drops as evening comes cooling the material of the gas tank. This creates a relatively cool container filled with warm air. When the air inside the tank hit the cool surface of the gas tank, it forms condensation. Most of this water evaporates back into the air inside the tank. Some of it does not evaporate but drains into the fuel inside the tank.

Water can create problems for your fuel system.

Actually, excessive water can create problems for your fuel system. Your car’s fuel system is made to deal with a certain amount of water without any real problems. It has filters to stop most water from reaching your engine. Small amounts of water are harmlessly vaporized in the cylinders. Too much water can cause the filters to clog until fuel cannot pass to supply the needs of the engine. Older gas tanks would rust. More modern tanks are not made from metal and do not have this issue.

Reducing condensation is not too difficult.

The best and simplest way to reduce condensation is to eliminate the surface area where it forms. This is done by keeping your tank filled with fuel. A full tank costs no more to run than an empty one once it is filled the first time. You buy gas every 100 or so miles and this keeps your tank mostly full all of the time. This will not entirely remove all condensation, but if you have 90% less open surface area, you will get about the same percent of less condensation.

You can insulate your fuel tank.

While they are not as popular today as a few years ago, a type of blanket is made to wrap around your fuel tank to keep the material of the tank from warming and cooling more rapidly than the air inside. This will result in a major reduction in condensation. The reason that these blankets are not as popular today is because of the increase in gasolines that are alcohol blends. Water will not mix with gasoline, but alcohol will. Since alcohol has some water in it, alcohol will mix with water. When water gets into a tank filled with gasohol, it can be absorbed into the mix and actually give you a small increase in the amount of fuel in the tank. This does not necessarily mean that you can drive farther because the water will not power your car. It just is a sort of filler mixed in with the fuel.

If you do get too much water in the tank, you can add products to absorb it.

For those who are losing the battle against condensation, there are about a dozen good products on the market that essentially add more alcohol or a similar chemical into the gasoline to make it more compatible with water. This will let the water mix with the fuel and be burned through the engine.