How to test fuels for alcohol content

by Contributor

Alcohol doesn't have as many BTU's as gasoline, and it doesn't perform the same. I will show you how to test your fuel for alcohol content.

Collect a fuel sample from your car's fuel supply. I use a clean 1 liter pop bottle that is clean and dry (so you contaminate your sample).

Pour 90 ml of your fuel sample into the 100 ml graduated cylinder. Add 10 ml of water to the cylinder and cover the top with your finger and shake.

Let the fuel sample set for 10 to 15 minutes. The alcohol will combine with the water and separate from the fuel. Read the line where it separates.Now comes the calculation, with 100 ml = 100% Looking at the cylinder, the way we would read this is: The line is on the 53 and we know 10% was water to begin with. The water will settle to the bottom because water is heavier than gasoline. 53-10=43 This sample would be 43% alcohol, which would be way to much for a 10% blend and most cars would run very poorly if they started at all.


  • close Fuel is flammable, be careful with gasoline

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