Here in the U.K. we’ve changed from E5 (5% ethanol) to E10 (10%} although E5 is still available but not at all garages. I was under the impression although E10 might affect engine performance/economy it wouldn’t damage it. It would, however, affect rubber seals in carbs etc. Found this on Hagerty:
What’s the problem for classic cars?
Although many cars run on E5 without significant problems, doubling the amount of ethanol in the fuel can cause a variety of issues in olders cars. Ethanol is hygroscopic, which means that it absorbs water from the atmosphere. And that water, in turn, finds its way into your car. It can lead to condensation in fuel tanks, fuel lines and carburettors and cause corrosion in brass, copper, lead, tin and
zinc components.
As ethanol is also a solvent it can eat through rubber, plastic and fibreglass, so hoses and seals are likely to perish more quickly because of the higher concentration of ethanol in E10. In Department for Transport tests, problems identified included degradation to fuel hoses and seals, blocked fuel filters, damaged fuel pumps, corroded carbs, blocked injectors and corrosion in fuel tanks. Rubber is particularly affected. The Federation of British Historic Vehicle Clubs (FBHVC) has a list of ethanol-friendly materials that can be used as replacements.
Finally, ethanol isn’t as energy dense as petrol, which means that the fuel-air mix could be leaner and, ironically, fuel consumption could actually be slightly higher than using E5 or ‘pure’ petrol