The price premium for "premium" fuel is usually paid to get more octane, but one of the side effects is that in many cases it does not have alcohol, while the "regular" gas does. Here in Alberta, all regular gas has ethanol, but some premium does not. I certainly would not pay for premium in a tow vehicle, but for a lawn mower that has seals which would be damaged by alcohol the premium gas would make sense. My small engines all get gasoline with 10% ethanol - no issues yet.
Some F-150 engines are "flex fuel" capable, and are fine with ethanol all the way up to E85 (85% ethanol); however, the EcoBoost engines are not. This is a non-issue here, since I don't think you can even buy over 10% ethanol fuel even if you wanted it, but I understand it is something to watch for in some other areas.
The F-150 manual's section on fuel is quite clear - and contains some very specific and extensive requirements. On a cross-continent trip I don't know that I would successfully check for compliance of all the fuel I might buy, and I'm sure that this situation is far from unique to the F-150 or to Ford.
I find the pure-gas.org
site a little strange, because it is not about pure gasoline at all: according to its own about page
, it is entirely about ethanol in gasoline. Methanol is also used in gasoline, and is more problematic than ethanol. The F-150 manual also refers to other unacceptable additives, and this site does not address them at all. You could easily get fuel which is not acceptable to your vehicle but which is legitimately listed as "pure gas". If your only concern is ethanol, this looks like a great resource. Maybe they should just call it "ethanol-free".org?
Remember, this site has one, simple purpose: to list the stations that sell ethanol-free gasoline in the U.S. and Canada