We run a 3/4 ton Chevrolet Extended Cargo van with the 4.8, I run about 500 miles every day and get 20 mpg. It's a 2008 that I got new and now has 250,000. with no problems.
As I understand it Flying J was bought out by Pilot and they are the ones who are changing the Restaurants over to Denny's. The restaurant's used to be run and owned by the Flying J's owners daughter and her husband.