2/3  cup  Sugar
2/3  cup  Water
1  cup  Grapefruit juice
1/2  cup  Orange juice
3  tablespoons  Grenadine syrup
28  ounces  Ginger ale, chilled

Combine sugar and water in saucepan over low heat. Stir until sugar is dissolved. Bring to boil and boil 10 minutes. Cool. Add sugar syrup to grapefruit and orange juices. Chill thoroughly. Add grenadine and ginger ale just before serving.