Until a couple of years ago, it was E10 at my local petrol stations, or nothing. My old bikes and 1950s car performed fine, once I'd made sure fuel pipes were able to live with ethanol. On my bikes I worked out where to turn off the petcock, so I ran out of fuel in my drive. Just because it felt sensible to store them with as little fuel in the bowls as possible.
My personal view, having looked into it a few years ago, additives main effect is to lighten your wallet. Some swear they protect even their daughter's virginity, others that they're laced with micro-chips sending your riding habits to Beijing (they're welcome
). I've found I haven't needed them.
One caveat, my older bikes do get fairly regular use, probably at least once a fortnight, throughout the year. If I was going to lay one up for a few months over winter, I'd empty the tank and carbs. If I couldn't store the tank in the warm, I'd maybe coat the tank with some 2T oil, to reduce the effect of condensation.
