I second what MiniMe and Schwert are saying, and I hang out at a store where lighters are sold and repaired. Fuel evaporation is virtually the only reliability problem I'd worry about with Zippo. But I carry a few little butane lighters for backup.

There are two alternative work-arounds for the Zippo fuel evaporation problem. 1) Zippo sells an aluminum o-ring sealed travel fuel bottle which holds around 3 fills. It can hang on a key ring. I've verified that it will hold fuel with no evident loss for 2-3 months. It isn't much bigger than a roll of lifesavers candy.. cost me around $12.00
or..2) Check out the AUSTRIAN Army Surplus lighters sold by Cheaper Than Dirt from time to time. They are flint/fuel lighters, and for some reason (they seal very tightly) they hold fuel with no evident evaporation for 2-3 months. Verified across 4 users and 8 lighters, so far! Cost only $5-$6 each.