Interesting problem. My Dart does the same thing and pisses me off every time it happens. I can't remember if Oregon uses the vapor recovery deals on their filler hoses? I've pumped my own at Pilot/Flying J in Oregon. Only diesel though. I don't know of any mods except for maybe putting that little trap door "unleaded" thing in the top of the filler tube. I think the problem is related to the filler end not going down the tube enough because of the vapor recovery thing on it and it won't shut off until the fuel is going over the bend. You could just tell them to put X many gallons in it? Carry a utility jug?