Ethanol acts like a corrosive agent to natural rubber and some older engine gasket materials. There are over 40 different blends of fuel used in the USA today, and even MORE harmful to natural rubber are the chemical additives in the fuel. Newer engines parts use mostly nitrile, silicon, viton, ptfe, and other fluoro-elastomers. These are not only MUCH less affected by the ethanol, alchohol and chemical additives, but they also handle much higher temperatures, pressures, and are low permeable. (remember the fuel smell in your old garage with that old car? Fuel could actually permeate the old carbureted material fuel lines and what you smelled was the fuel vapor that had seeped right through the hose!) So yes, the materials used in your engine have a BIG impact on it's use with new fuel blends.
Mark Davis
Palm Beach Gardens, FL
amateur photographer, hot rodder, motorcyclist, adventurer
"Four wheels move the body. Two wheels move the soul."