[rotorwrench]

There are a fair amount of complex hydrocarbons that go into the final batch of fuel that you buy from the pump. Some are very light distillates and some are gasses then there are the complex processes that make the naphtha more efficient in the burn. Some of these processes use catalysts in the conversion and none of the mix gets along well with water. Internal combustion engines don't run well on water contaminated fuel. If you want to take your already less than spectacular fuel and contaminate it further then be my guest but you may notice that the vehicle doesn't run as well as it should and it will likely get unstable even faster than it already does by normal absorption of moisture from natural condensation in the tank.