Our 2003 Silverado 1500 4.8L Quad Cab w/ a 6 foot bed gets about 16 mpg with Walmart Gas. Now if we pay the extra 10 cents and get gas at Marathon or Speedway we get 20+ miles to the gallon. Walmart gas contains up to 15% ethanol, while Speedway and Marathon is straight gas. Do people realize that if this the case, we might as well start paying more for straight gas. Really, the more expensive gas goes farther and keeps you from filling up more. I notice that my 1972 Chevy Bel Air 350 2bbl gets better gas mileage with Marathon/Speedway gas but I never have figured up the fuel usage on it.
Asked by Memaw