Same as above, generators, rotavator and before winter bikes, run them dry to prevent evaporation leaving varnish in the carb, and I use the fancy shell petrol especially before storage.
There is a fogging spray you can use for 2 strokes. Turn off the fuel and just before the engine dies spray into the air intake. I tend to use WD40 down the plug hole.
And yes biofuels are rubbish - not only that but the growing processes are destroying wild life and the planet but it is renewable so it has to be good........
I have a two gallon can of two-stroke mix at least ten years old. It's securely capped and still (to the best of my knowledge) has most of its volatiles.
About two years ago I refilled a chainsaw with it, and it fired up no problem. Last year I did the same.
I really doubt any petrol from a pump now would keep so long.