Can Sugar in the Gas Tank Really Kill Your Engine

Weve all heard the urban legend that pouring sugar into a cars gas tank will kill the engine. Does the sugar turn into a gooey sludge, gumming up the moving parts, or does it caramelize and fill your cylinders with nasty carbon deposits? Is it really the nasty, evil prank its made out to be? If the sugar got to the fuel injectors or cylinders, it would be bad business for you and your car, but that would be because any particulate will cause problems, not because of the chemical properties of sugar. Thats why you have a fuel filter. A Solubility Experiment Even if sugar  (sucrose) could react in an engine, it  doesnt dissolve in gasoline, so it cant circulate through the machine. This isnt just a calculated solubility  but rather is based on an experiment. In 1994, forensics professor  John Thornton at the University of California, Berkeley,  mixed gasoline with sugar marked with radioactive carbon atoms. He used a centrifuge to spin out the undissolved sugar and measured the radioactivity of the gas to see how much sugar dissolved. This turned out to be less than a teaspoon of sugar per 15 gallons of gas, which isnt enough to cause a problem. If you have less than a full tank of gas at the time its sugared, a smaller amount of  sucrose will dissolve because there is less solvent. Sugar is  heavier than gas, so it sinks to the bottom of the gas tank and decreases the amount of fuel you can add to the auto. If you hit a bump and some sugar gets suspended, the fuel filter will catch a small amount. You may need to change the fuel filter more often until the problem clears up, but its not likely the sugar would clog the fuel line.  If its a whole bag of sugar, then youll want to take the car in and have the gas tank removed and cleaned out, but this is not a difficult task for a mechanic and will run you about $150. Thats not good, but infinitely better than replacing an engine. What Can Kill Your Engine? Water in gas will stall a cars engine because it disrupts the combustion process. Gas floats on water (and sugar does dissolve in water), so the fuel line fills water rather than gas, or a mixture of water and gasoline.  This doesnt kill the engine, however, and can be cleared up by giving a fuel treatment a few hours to work its chemical magic.