STC AvGas

The Puregas app lets you know the closest alcohol free gas. Only a couple of places locally here and usually available near boating. I get Countrymark 90 octane. Sure helps to avoid lead fouling.

Alcohol absorbs the water so it can't be drained/sumped. That moisture in the system can cause corrosion and other long term problems. If the fuel becomes saturated with water (possible in our open vented fuel systems), then phase separation occurs where in all the alcohol and water separate out and settle to the bottom of the tank. That could be a couple of gallons of alcohol/water mix sitting in the bottom of your tank, and your engine won't run well on a pure water/alcohol mix. Alcohol is also corrosive to plastic, rubber, and some metal components in older engines not designed to run on alcohol. Our old Continentals fall into that category. Example: Some of the Stromberg carburetors have a neoprene needle valve that swells in the presence of alcohol and can cut off fuel. If you still have cork floats, the alcohol will dissolve the shellac and cause the cork to deteriorate and flake, potentially causing blockage.

And, of course, the whole reason we do anything....insurance. The engines are certified to run on alcohol fuels, so if there is an insurance claim and there is alcohol in the fuel......you can guess the results of that.

I have never tried it, but I understand you can put a few drops of water into a vial of gasoline and if the water disappears, alcohol is present. If the water settles to the bottom of the vial, the fuel is alcohol free.

Thanks Ron for your input. How does the presents of alcohol affect the engine and is there a way check its presents in the gas?

What do you have available without alcohol? You may not have much of a choice in the matter.

If you want to use Gasoline in your coupe, what octane (regular, mid grade, or premium) is best (87, 89, or 91)???