As long as you run fresh 93 fuel with ethanol regularly, it shouldn't be a problem. The problem is when Ethanol sits for a long period and absorbs water out of the atmosphere. I personally would choose the 90 w/o Ethanol and add 16 to 24oz. of Torco accelerator to a tankful to bump up the octane a bit, because mine sits for very long periods between use. The downside is that it adds $10.-$15. per tank. So if you daily drive it, you may not want to spend the extra money. When I occasionally track the car, I add an entire quart to tank. Or I use the Ethanol free race gas at the track; and I DO notice the difference. As I understand it, the extra octane is also good insurance for not going lean @ w.o.t. . You'd be fine with just 90 w/o ethanol. Or use the 93, and then fill it up with Ethanol free if it gets put away for the winter. I sure wish we had 93 Ethanol free here for daily use!