Zippo lighter fluid is recommended for filling Zippo windproof lighters, hand warmers, and fuel canisters. Zippo lighter fluid comes in 4 oz. and 12 oz. cans. According to Zippo, their lighter fluid is engineered to work best with their lighters and flints. While some people have reported success using other lighter fluids, such as Ronsonol, it is recommended to use Zippos own lighter fluid for best results. To fill a Zippo lighter with lighter fluid, follow these steps:

1. Remove the inside unit from the case.
2. Turn it over and lift the felt pad to reveal the packing material in the fuel chamber.
3. Slowly saturate the packing material with lighter fluid. Stop filling when the fluid reaches the top of the packing, or begins to change color.
4. Insert the inside unit back into the case, making sure to wipe any excess fluid from the lighter and your hands before igniting the lighter.
5. Using your thumb, strike the flint wheel to ignite the lighter.

It is important to take caution when filling a Zippo lighter with lighter fluid and to do so away from any source of fire or flame. It is also recommended to keep the lid of the lighter closed when not in use and to refuel before each outing, as lighter fluid can evaporate even when the lighter is not used.