The Wednesday promotion adds $1 per gallon on top of whatever that offer already pays and any cash back you earn from selecting gas as your monthly cash-back category, so you have the potential to save more than $1 per gallon. Rewards are posted as OnePay Points that you can redeem as a deposit into a OnePay account and use for future gas purchases or anything else you pay by card. THOMAS BARWICK/GETTY IMAGESWhat you need to do to save at least $1 per gallon on gas this summerTo save on gas through this OnePay deal, you'll need to take the following steps:Download and open the OnePay app, and go to the Rewards section. Activate a gas offer at a participating station near you. OnePay debit cards and OnePay builder cards can earn either way.