We now know that the alcohol in the current gasoline consumes light alloy components. That already works with 5% admixture. With 10% the gluttony of the aggressive substance can actually make holes in carburetors.
So refuel as much as possible without alcohol and consider draining the entire fuel system for longer periods of downtime or filling it with Aspen gasoline. That may be an investment, but it has proven results.
A tip that we hear more and more often is that about adding 2-3% two-stroke oil to a full tank of gas.
it may fall under the same flag as the addition of a liter of diesel to a tank of gas when it comes to side valve engines.
What has been proven: conventional rubber gasoline hoses dissolve when alcohols are used.
If there is a chemist among the readers: Explanation is welcome!