Based on Doug's suggestion of only buying diesel fuel from a truck stop, I made one of my very infrequent (15mpg while towing the Overlander) pit stops at the Flying J at Lake City, Florida. I may be the only one not to know of their fantastic "RV islands". Big wide parking lot, totally separate RV fuel area, pull through style with high speed pumps and a sanitary dump station. The entire facility is a class act...

Does anybody know if they are nationwide? -- I realize I could have asked when I was there but, I didn't...

David Crook