Re: old gas , Can it be used?
Can the gas be used? Yes. Is there a great enough quantity of gas for its dollar value to mitigate the potential loss of use of your vessel if it runs poorly or not at all because the old gas fouls your carb or fuel injection system?
Most guys are going to advise you to dump an equal amount of fresh gas into the old to "freshen it up", or ad SeaFoam or some other fuel stabilizing product. That may work, IF you don't have particulate matter suspended in your old fuel, which when blended with new gas, will STILL be contaminated fuel. When in doubt, use a good inline fuel filter, and a fuel water separator, and change them frequently. Good luck.