8.6 What is "stale" fuel, and should I use it?
"Stale" fuel is caused by improper storage, and usually smells sour. The
gasoline has been allowed to get warm, thus catalysing olefin decomposition
reactions, and perhaps also losing volatile material in unsealed containers.
Such fuel will tend to rapidly form gums, and will usually have a significant
reduction in octane rating. The fuel can be used by blending with twice the
volume of new gasoline, but the blended fuel should be used immediately,
otherwise teh old fuel will catalyse rapid decomposition of the new,
resulting in even larger quantities of stale fuel. Some stale fuels can drop
several octane numbers, so be generous with the dilution.
http://science.howstuffworks.com/fra...ine-faq/part1/
Right from a horses mouth other then my own, the old gas from my car is now killing unwanted grass in my driveway.