Here in the northwest corner of what passes these days for a nation we’ve been on E10 for about 35 years. In that time I have never had a problem nor seen a problem that I can say is a fault of E10. Maybe our regional refinery in Anacortes is unusually good at blending or maybe it’s Alaskan crude as a foundation or they use better booze in their blend but whatever the cause I have yet to see a part failure that I could conclusively grunt and say alcohol did it.
Couple years ago on my Heritage I was riding to a friends house in Yakima and decided to take the scenic route over the back side of Mt Rainer rather the the Interstates. When on my hard tail which only has a 3.1 gallon king tank on it I have to stop at Greenwater which is the last fuel stop for the next hundred miles and from my house to Greeneater burns out 70 miles of fuel. As a habit I stop there on the Heritage just to cover my contingencies but it’s 5 gallon tank isn’t usually a problem. This last trip the only fuel they had at Greenwater Chevon was leaded so I just decided to press on rather than contaminate the Harley with leaded fuel which has never been in that tank nor in the tank of the hard tail.
Leaded fuel at a regular pump is unusual.
Ethanol will absolutely eat rubber parts not meant for exposure, not to mention all the solvents like toluene that are in pump fuel now---we use toluene to soften tires, and it will simply melt them if you get too aggressive with the amount and duration.
I don't do driveability anymore buy have heard that some pump fuel is not E10, but E30. Will work in FI engine with feedback but carbs are just controlled leaks and don't understand.
I should invest in the test kit.