Ah, lightbulb - Thanks, think I shall try some stabil. My new mower is very sensitive about petrol quality and the makers suggest draining the carbs if left for more than 2 weeks. My winning solution for many years with different mowers is to top up the tank before trying to start the mower.
I keep my petrol in a standard 5ltr can but with an old (very old) champagne cork in the spout, to prevent evaporation of the more volatile elements of the petrol. Seems to work.
Re storage against shortages - is this really viable? How much would you need to store to meet even short terms needs, my guess is quite a lot, unless its for a small say, generator.
Propane gas cylinders are easier and last quite a long time, you just need to get the right sort of machine/equipment that you envisage needing it for. If its for transport alone I'd say forget it. Even a small motorcycle uses quite a bit. If you envisage having to travel during a major shortage then you need an alternative contingency plan incl say, a bicycle. Covid was a classic example.