Abstract: A stabilized composition of matter comprising a fuel oil, such as gasoline, ethanol, small amounts of water and a stabilizing amount of an additive which is substantially insoluble in water, but which is soluble in ethyl alcohol and gasoline and is effective to prevent the separation of the gasoline-ethyl alcohol solution into two distinct phases; said additive being n-hexylalcohol, hereinafter, n-hexanol. The invention also includes a method for stabilizing gasoline, that is, for preventing or retarding the phase separation of gasoline-ethanol mixtures in the presence of small amounts of water, and this being the case when the temperature of the gasoline-ethanol mixture has been reduced to below 20.degree. F.