Acetone as a fuel additive is a controversial subject. Many drivers report a 10 to 15 percent increase in fuel efficiency when adding small amounts of acetone to their gas tank. Some mechanics claim that any increases in mileage are due to errors in testing. You can test the effects in your engine by adding acetone the next time you fill your tank.
Acetone reduces the surface tension of gasoline, which leads to more complete vaporization and therefore more thorough combustion within your engine. Since your vehicle is burning the fuel more completely, your mileage should increase. In addition to better mileage, users of acetone as a fuel additive have reported an increase in horsepower, longer engine life and reduced hydrocarbon emissions.
Pure acetone can be purchased at most drug stores, though it's more cost effective to buy it at home improvement or paint supply stores, where it is sold as paint remover. Only add 100 percent pure acetone to your fuel system--acetone sold as nail polish remover could contain dyes or perfumes. Acetone can irritate eyes and skin, so take appropriate precautions when handling it. Since acetone is flammable, treat it as you would gasoline: Store only small amounts in a sturdy container in your car. Use a glass graduated cylinder (available at pharmacies) to measure the acetone when you fill your tank. Check your manual to determine the capacity of your fuel tank. Acetone has higher octane rating than gasoline, so begin by adding 1 ounce of acetone per 10 gallons of gasoline to let your car's octane sensors recalibrate to the higher ratio. After a tank or two, increase your mixture to 3 ounces per 10 gallons. Add the acetone before the fuel to ensure that it mixes evenly. Be careful not to spill acetone on your car's body, because it can dissolve paint and plastics.
Because of the increased octane rating of acetone, your car's check engine sensor may come on if you discontinue use of the fuel additive. Resetting the anti-knock sensor will clear this error. The effects of acetone seem greater in carbureted engines rather than fuel-injected systems, though fuel-injected diesel owners have reported a boost in mileage using acetone. If you have a diesel engine, use as smaller ratio of acetone: no more than 2 ounces to 10 gallons of fuel. Some vehicles, such as the Toyota Prius, have a synthetically lined fuel tank or other plastic parts that could be damaged by the solvent action of acetone.
