Popular opinion holds that gasoline is unstable and lasts six months at the most; some claim it loses its “edge” after as little as two weeks. Practical experience seems to show that gasoline can be stored without special precautions for years with no noticeable deterioration. Storage conditions are supposed to make a huge difference, but in my observation they don’t. What’s the straight dope on this? –Sean Costall, via e-mail
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The shelf life of gasoline depends on the type of gas and the storage conditions and can range from a couple months to a couple years. One wild card is that gas you buy at the pump may already have been in storage for anywhere from days to months.
The second cause of bad gas is oxidation–some of the hydrocarbons in the fuel react with oxygen to produce new compounds, almost all of them worse than what you started with. When oxidation becomes a problem, you’ll know it without lab tests–the gasoline gives off a sour odor. If you pour some into a glass container, you’ll see it’s turned dark, and you might find small, solid particles of gum. Using oxidized gasoline is a bad idea, since the gum can clog your fuel filter, create deposits in your fuel system (especially the injectors), and generally hurt performance.
There’s no easy way to get rid of bad gasoline, but don’t be a pig and dump it down the drain. If you really can’t use it, contact your city or county to ask where you can dispose of it legally. Some people recommend using it in a lawn mower, but you risk gumming up the mower’s works instead. What’s left, tiki torches? Better to time your gas consumption and purchases so you don’t need to store any–gas prices being what they are, no sense tying up cash in something that may just go to waste.
