Any alcohol fuel (methanol, ethanol, E85) needs proper tuning and procedures. Some pointers:
1) Get the idle mixture lean enough, rich milks the oil
2) Stage at 160-180F water temperature
3) Heat to 190-200 F before shutting down at the end of the night and pull the breathers for a while to let things evaporate.
4) Plug fuel vents, reinstall breathers during storage between weekends.

I never had any problems with the oil with E85 or methanol and I used Brad Penn all the time since I ran a flat tappet solid lifter cam. 2008-2013.