Wako’s Fuel 1 (suppresses fuel oxidation degradation and fuel tank corrosion).
How much benefit we’ll actually get is still unknown, but it might be a good idea to incorporate it into our maintenance menu and administer it regularly.

Depending on tank capacity, it looks like we add about half a bottle per bike. Since the Fuel One container doesn’t show the volume, I got a measuring cup ready.
These days there are some really great products with volume markings visible from above. I ordered one for fork oil too, with a different capacity.

Looks like plum wine or a urinalysis sample? We want to keep the carburettor from corroding as much as possible. And it’d be great if we can also suppress tank rust.
If you’re interested, you can add it along with an oil change or other maintenance. Just note that Fuel One alone isn’t possible.