At participating Walmart and Murphy USA gas stations, get 15 cents off per gallon when you pay with a Walmart credit card or 10 cents off per gallon when you pay with a Walmart gift card. That's tied with our mention from a year ago and one of the strongest gas discounts we've seen from any merchant. (Walmart typically offers a smaller discount to cardholders throughout the year.) Select states are excluded. Deal ends September 8.