Testing Procedure

1. Using a 100 ml cylinder with 1 ml graduation marks, fill with fuel to the 90 ml mark.
2. Add 10 ml of water to bring the total fluid volume to 100 ml and install a stopper.
3. Carefully loosen stopper to release pressure.
4. Close the stopper and shake vigorously again for 10 to 15 seconds.
5. Carefully loosen stopper to release pressure.
6. Put the graduated cylinder on a level surface for approximately 5 minutes to allow adequate liquid separation.
   Fig 1: Testing Gasoline

   Courtesy of GENERAL MOTORS CORP.

If alcohol is present in the fuel, the volume of the lower layer, which would now contain alcohol and water will be greater than 10 ml. For example, if the volume of the lower layer is increased to 15 ml it would indicate at least five percent alcohol in fuel. The actual amount of alcohol may be somewhat greater because this procedure does not extract all of the alcohol from the fuel.