I ran E10 in my 1946 C85 Continental that had Goodyear rubber fuel tanks at Altitudes up to 15,000 Feet above sea level for 15 years didn't hurt a thing. I also put 2 tanks through my 2002 BMW 330CI 1st tank was about 2/3's E85 first time I started it was kinda of rough bought a can of ether didn't ...