Citgo Good Rewards is simple
1-Enroll by clicking link above(You’ll need a text-enabled mobile phone and eligible Visa® card to get started.)
2-Use your enrolled Visa® card to make qualifying credit purchases at participating CITGO locations.
3-After 8 qualifying purchases of $20 or more, you will be sent redemption instructions and a unique code to request your $15 CITGO Gift Card.
-Promotion ends 09/20/12 / about a 9.4% rebate
Info from emptynesterstravel.com