As rightfully indcated above, DO NOT use fuel that has been left exposed to the air for any length of time.

The fuel absorbs water, and that causes all sorts of problems.


Sealed jugs that are kept out of the sun, can often be used without problems after many years of storage. While water may appear to condense on the inside of the jug, what appears is what is already within the jug, so it does not increase the amount of moisture in the fuel.

People have erroneously assumed that because heating and cooling can cause this condensation to form, AND because water in the fuel is bad, that it follows that leaving fuel on a concrete surface ( which causes this internal condensation ) will ruin it. That is not necessarily so.

However it is best to try to limit the amount of temperature change to assure the stability of the chemicals.