So planning to take extra fuel for this weekend I experimented, I purposely overfilled one of my cans, the other is filled to the full line as it should be. I then tossed both up on my rack in the sun, on a 90 degree day. After a few hours, you can see the overfull can on the left swelling. The one on the right shows no outward signs of deformation. Neither has leaked a drop yet. These are both around a decade old wavian Jerry cans.
I can’t wait to hopefully pick up a few of the specter MFCs when I head to Canada in a few weeks though to compare. :thumbs up:
EDIT-
Picked up the MFCs and filled them each with 20l of ethanol free fuel. Threw them on the roof same as I typically do my Wavians. They swell like balloons! Not a drop leaked, but it sure looked funny. A few hours in the sun after unstrapping them back home and the dent left by the strap had disappeared, so I guess all good, but I wouldn't put them in a tight fitting holder, depending on design you may not be able to remove them when you need them!
MFC1 by
Erik, on Flickr
MFC2 by
Erik, on Flickr