If the vehicle is designed to use E85, it will use it in whatever mix
or time of sitting you desire. The two issues are mixture control (E85
has to be run richer and the computer system must be able to deliver
the extra fuel) and plastic/rubber compatibility with ethanol.
What, after all, is the difference between letting ethanol base fuel
sit in the car a while and driving it a lot and filling it up? A
properly vented tank isn't going to allow all that much water pickup,
which is the only problem I can think of with letting it sit.
Peter
