Drygas is an alcohol-based additive used in automobiles to prevent any water in the fuel from freezing, or to restore combustive power to gasoline spoiled by water. The name Drygas is actually a registered trademarked brand name, owned by Cristy Corporation. It is a liquid that is added into the fuel tank, that absorbs the water and keeps it in solution. Some brands contain methanol and some contain isopropyl alcohol.
Some states require a 10-15% ethanol solution be sold at refueling stations. Most current gasoline-powered automobiles can safely run up to a 10% ethanol solution without any modification. However, at 15% or above older vehicles may require replacing the fuel lines to prevent degradation and rupture, and the electric fuel pump may need modification to prevent ethanol "dry rot". The belief that dry gas is not needed because of the significant amount of ethanol is largely true because ethanol is a drying agent. Due to this fact it has an affinity for water which can be present in the atmosphere, but since environmental concerns have caused fuel systems to be closed, it works effectively on the moisture inside the tank which was already present. The water that has been "absorbed" then reduces issues with freezing fuel lines. The action of adding dry gas (anhydrous methanol or azeotropic iso-propyl alcohol) is suggested to mix with absorbed water lowering the freezing point of the now water and alcohol solution, lower than it would mixed with ethanol, allowing the fuel lines to better resist freezing, while non-frozen water will be removed when either solution is used by the engine.