I have used original recommended fuels and naphtha in all my fueled hand warmers and it works just fine we can get it here by the gallon so no fuel shortage here I do find the Zippo does not get very hot and only seems to keep a pocket semi warm more disappointing than anything the older vintage ones run much hotter and to me work better at keeping me warm the basically the Zippo was a disapointment even the reusable chemical ones are hotter their only drawback is they last a couple hours tops but that still can make a difference of keeping your fingers or toes from frostbite... but if its all you can find go for the Zippo still better than nothing....