Unfortunately, the stuff that evaporates out of gasoline is also the stuff that makes it potent.
In events like the recent hoarding of gasoline storing it in unsealed containers, the gas loses enough potency to be useless within a few weeks. Stored in sealed containers (limiting loss) it can last many months. Stored in sealed containers with a gas stabilizer can last for even longer, the stabilizer reduces the potency but it harms it less than the time on the shelf would.
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