The only real downside of a good Zippo lighter is that the fuel evaporates too quickly. When I refill mine, sometime I get a little overzealous in the amount I add. That practice often leads to some exciting times the first time I use it.
I lift the felt pad and pour the fluid directly on the "cotton" until the liquid just comes up to the top of the cotton and replace the felt. Then I light it and let it burn for a few seconds to burn off any excess that might have spilled onto the outside of the innards. I don't worry about the excessive flaming... what I hate is when it's overfilled and then proceeds to leak in your pocket and you end up with a red, burning spot on your leg that lasts an hour or more.
after each fill, i light it and let it burn till its not a torch anymore then extinguish it wipe it down and move on. Also for keeping the fluid longer i have heard good thing about using a "ranger band" i havent done that yet bc i have no tubes to make one with.
This is also the level I fill to and it hasn't caused problems. I also run them with a ranger band to slow evaporation of the fluid (probably helps reduce/eliminate leakage too).
Below, ranger banded Zippo on the left, naked Zippo on the right. Just roll it down to light, and roll back up when done.
I know a guy that worked in a body shop (late 70's). He used to fill his Zippo with paint thinner, I don't remember what it was though, and yes, I thought he was crazy for doing so.
1.) Fill Zippo
2.) Set full Zippo on folded up paper towel, to catch any leakage, for a few minutes.
3.) no leakage, put the case on, close it up and go about your day. If it's leaking onto paper towel depress felt with paper towel to soak up overage.
A leaking Zippo will give your a leg, (or whatever it leaks on) a chemical burn, that takes longer to heal than a cut from your newest knife.
Consider Clipper brand lighters if you wish Bic's were more reliable, refillable, and more wind-resistant. They're cheaper than zippo's and collectable. Zippo's are way cooler and even more collectible, I own both, but me personally, I prefer butane that doesn't evaporate as quickly as zippo lighter fluid.