There are several threads on this forum which include most of the info you'd need to switch over to E85. I haven't had issues with my gas tank yet, but it is likely a good idea to change out the filter before you switch over, and then monitor it on occasion just to make sure it doesn't get clogged up. I have been running E85 for around 2 months now and haven't had issues yet (that I know of). haven't changed the fuel filter since changing it right before the "switch over" either.