Possible Clues:

• Coca-Cola brand
• Citrus-flavored diet drink
• Citrus soft drink
• Sprite alternative
• Diet Squirt alternative
• Grapefruit-flavored soda
• Citrus soft drink introduced in the 1960s
• Grapefruit-lime soda brand
• Grapefruit-flavored drink
• Grapefruit-flavored diet soda