The Free Fillin' Rewards Program allows you to earn free gasoline or airline miles for filling up at your local Tesoro station. Every time you fill your gas tank at a participating Tesoro location, you receive a stamp. Once you collect enough stamps, you may redeem your booklet for up to $5 off a gasoline or diesel purchase. You will be rewarded right at the store. That’s instant savings! For more information on the program, check out the link to the Free Fillin' Rewards Program.