For EDC, I also carry a mini Bic or a peanut lighter. I carried a mini Bic for about a year with no leaking issues. I prefer the mini Bic because it is more rugged and just works. I'm currently carrying a peanut lighter to test real world carry conditions. The peanut lighter is slightly smaller and nicely fits on a key chain.

I have had no leaking problems with either of these. I have left a peanut lighter alone for a year, and it still lit up. If your peanut lighter leaks, there may be a problem with the O-ring. I personally have not found suitable replacement O-rings on the Internet. If anybody has a link to the correct O-ring, then please share.

For ensuring gas doesn't leak on a mini Bic, I cut a bike inner tube thin enough such that it fits the gap underneath the button. I installed the bike inner tube there and double it over for added tension, like one can do with a rubber band.

For the peanut lighter, I wrapped the exterior with bike inner tube, which is not intended to prevent leakage. Rather, the bike inner tube is tinder and also dampens clanking with other objects.

In everyday situations, I rarely use my lighter for anything. It's mainly there "just in case". I'm contemplating moving back to a tiny ferro rod and scraper to carry on my person at all times. That way, I don't have to worry about temperamental issues like fuel leakage.