I heard about using biodiesel in place of two cycle oil back in December and did some checking over the internet. Most people say that it doesn't work too good. I was interested in because I run a lawn care service and thought it would be a good way to lessen pollution. I think going to one of the soy based two cycle oils is the way that I will go. You can find info on those here.
Soy Based Products
As far as using E85, it might be hard on the plastic and rubber parts. I think E10 is probably safe for most things, maybe not really old equipment, but E85 may be pushing it.
