A lot of engine literature warnings will say not more than 10 or 15%.
We aren't getting away from using it.
Those that recall the fuel line freeze up, this is mfr's remedy.
Plus it accumulates in the storage tanks naturally.
Condensation is a natural occurance and alcohol will mix with water to rid of it through combustion in the engine.
At my young age, lol...
You could still maybe see me rolling down the highway, on my motorcycle, pulling a trailer with camp gear, smiling, beard in braids...
Feeling The Wind! (FTW)