Use old gas as varsol that’s what it is great part cleaner.
Make it into gel fire starter.
If not too old and you are in need for it to use as fuel, separate the water, strain any solids then add 500 ml of pure alcohol. It will burn rough but will go… this is last ditch effort
If you have a tri fuel military truck engine strain check the water trap in fuel line and happy trails, those will burn strained used motor oil.
If you get premium gas it has no ethanol and will last muchance longer. I store in teflow lined 50 gallon drums they are helicopter fuel drums. It runs our 2 stroke 4 stroke and crv after 6 months no problems. It is in a shaded shed but not protected from tempretures 38+ to -40 c