Purchase them in bulk: Amazon.com: Zippo 6 Genuine Flints: Zippo Lighters: Sports & Outdoors Insert at least one wheel worth just encase the previous owner wasn't concerned with your survival. LOL JMHO.
I noticed many moons ago that disposable lighters never seemed to run out of flint before they ran out of fuel. I smashed....er, disassembled a couple and verifeid that they do have extra long flints, and they fit in my Zippo. That still makes a disposable lighter that is out of fuel almost useless.
I have to admit that I have started many a fire n the boy scouts using flint and steel... An empty disposable just seems to Keep the flint and steel available and still fairy easy to start a fire if you need to....
I'm not sure, I only buy a can or two of butane at a time. At least months, maybe a year or longer in a cool, dry, dark cabinet.
Fuel in my zippo out today. So lasted until yesterday. That would make it about 3 1/2 weeks, which is about normal stored with just a ranger band.
I have carried a Zippo for years despite the fact that I've never smoked. I always carried it in my pants pocket but ran into the problem of having it run dry after a few days. I also developed a rash on my leg where the Zippo lay. I resolved both issues by carrying the lighter in a leather belt pouch/holster. They are cheap and work well. As a bonus my Zippo can go 3 or more weeks before drying out. Removing it from the body heat makes a huge difference. Remember- these pouches are not air tight!
I got a big smile on my face this morning. Found my 1960 Zippo, that was still in the nitrile glove. I had put it in the console of my car and forgot about it. I've been doing a lot of lantern repair and using a mini torch, so I had left the Zippo sitting there since 30 July...and it lit right up. Proves the point that without evaporation, the Zippo design can be stored full of fuel for long periods.
Even an empty Bic can be useful Turn an Empty Bic Lighter Into an Emergency Firetool: Repurposing Things Most Folks Throw Away
I use a chunk of ten speed bike tube around the lid, fuel lasts around a month if not used, also I run white gas in mine