Ethanol is hygroscopic, which means that it attracts moisture from the atmosphere. The water separates in the fuel mix and then corrodes anything ferrious. This means the inside of steel fuel tanks, carb pots and steel fuel lines. The rust particles break off, get swirled around your fuel system and then block up in your fuel filter, carburettor or injection unit. It is a particular problem for classic cars, because we don’t use them all the time and therefore the fuel has more time to absorb water. The average classic does less than 1000 miles a year, which means that they use less than 50 gallons of fuel. The average modern car uses about 350 gallons a year which means the fuel inside is 7 times newer and has no time to absorb the water. Now this has been a problem for years, it is just going to get a little worse, so what can you do?
- Keep you fuel fresh – Try to use the fuel you put in the car within two months
- Install an inline filter at the tank and carburettor end to catch any debris
- Change fuel filters every year as part of your regular maintenance
- Don’t store the car with full tanks over the winter
- Store your car in an environment with low humidity, around 45 to 60% is about perfect
- There are fuel preservers on the market you can add to mitigate these issues when storing a car