Quote Originally Posted by liftlid View Post
Fill em with water and give it a try
you won't really get the same heat expansion as fuel though i would not have thought.

I have carried plastic fuel jerry not eh roof quite a few times. I make a point of tightening the caps with Multigrips before they go on the roof. make sure you have those multi grips to undo when you need to. as noted empty as soon as you can.