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We have developed and validated a simple, quick, in-expensive method for determining the methanol or hydrocarbon content of a methanol blend fuel (a mixture of methanol and gasoline). The method exploits the insolubility of water in hydrocarbons. Briefly, 50 mL of fuel is mixed with a like amount of water and allowed to settle; the volume of the upper phase is directly correlated to the amount of hydrocarbon in the fuel. Equations and graphs are provided which translate between the hydrocarbon volume measured and the methanol content or the hydrocarbon content of the fuel. This method and the graphs and equations in this report are valid for methanol fuels made with any gasoline or virtually any hydrocarbon mixture, provided there are not oxygenates such as ethanol or MTBE present in the hydrocarbon fraction. The accuracy and precision of the method are excellent, for mixtures of dry methanol and oxygenate free gasoline.

Fuel alcohols, such as M85 (a blend of 85 percent by volume methanol with hydrocarbons) and Ed85 (a blend of 85 percent by volume denatured ethanol with hydrocarbons), are inherently involatile at low temperatures and may contain soluble or insoluble contaminants. We explored the adequacy of existing specifications for M85 and Ed85 by studying fuel effects on cold starting and vapor flammability, and fuel contaminant effects on materials compatibility and filter plugging. These studies demonstrated deficiencies in existing specifications. Therefore, we developed General Motors specifications for M85 and Ed85 to improve vehicle performance and durability. Key features include a Cold Starting Performance Index to improve wintertime starting, a conductivity and chloride ion specification to reduce corrosion, and a particulate contamination limit to reduce filter plugging.