Hi,

I still have the trusty Zippo on me when I go out there.
I've been experimenting to beat the evaporation problem too.
I've found that taking some precautions will have the Zippo light up after two months.

To minimize evaporation try this:

a. Don't carry inside a pocket, as this is sure to speed up evap.
I carry mine in a leather pouch made by Zippo on my belt.

b. Wrap an inch wide piece of tight fitting bicycle innertube
where lighterbody and lid meet. This will dramatically
reduce evaporation and also make it splashproof. When mine
fell in a shallow pond and I quickly snatched it out it
was still dry inside and lit up on the first try. Just don't
take it scubadiving

c. I bought an internal tank for it. This is a little brass
affair that fits snugly inside the lighter, although you
must remove about half of the cotton wadding. I bought
the tank here: http://www.peak-berlin.com/
Hope this helps,
Regards,
Pharaoh.