How Long Can You Store Gasoline?

Q: I have several five gallon cans of gasoline in my garage that are to be used in a generator in case of a power failure. They have been there for several years as well as a tank full in the generator. Can this gas go stale?
-- C. S. Legum,
Norfolk, Va.

A: Gasoline does degrade or become "stale" during storage. How long it remains viable depends on several factors including the container and conditions in which it has been stored. The gas in your garage is long past its due date, though, especially if it was stored without the addition of a chemical stabilizer.
[Me and My Car storing gasoline]
Associated Press
Many folks store gasoline, as seen here after Hurricane Katrina. But gas can go stale after a few months.

I know it is tempting to use the fuel, especially with prices so high at the pump. Indeed, many times I have poured gasoline of questionable vintage into the tanks of cars, motorcycles and of course, the lowly lawnmower. Several years ago I inherited a roto tiller with a tank that had been half full for years. Of course, it started on the first pull and has run well ever since. Still, the instructions for outdoor power equipment like mowers, snow blowers and chain saws often recommend draining the tank if you don't plan to use the machine for a several months.

The American Petroleum Institute recommends taking old gas to an approved disposal facility after, at most, two years of storage. But the gas may have degraded beyond safe use by then. To be safe, the trade group says, you should avoid storing gasoline from season to season. For example, if you fill the gas can in the spring you should use its contents before the end of the year.

I haven't had any fuel-related problems. But I have heard enough tales of woe from people who have that I now avoid storing gasoline for more than a few months and always add a stabilizer to the container.