The spec on "E85" is:
"n the United States, the exact ratio of fuel ethanol to hydrocarbon may vary according to ASTM 5798 that specifies the allowable ethanol content in E85 as ranging from 51% to 83%.[1] This is due to the lower heating value of neat ethanol making it difficult to crank engines in relatively cold climates without pre-heating air intake, faster cranking, or mixing varying fractions of gasoline according to climate. Cold cranking in cold climates is the primary reason ethanol fuel is blended with any gasoline fraction."
So seasonal blend plus your storage issues. FWIW - I run straight methanol and between races (about 2~4 weeks) I make sure the fuel cell is full and the carb empty, plus WD-40 treat the bowls, needle/seat assemblies and pump shooters. After season, I pump everything dry, put some 110 in the tank and a gas carb on the motor and run it a bit to clear the lines. 110 will keep in the car all winter, no problem. Unused methanol goes back in the drum and the drum sealed up tight. This is also done after every race. Thursday before the race I pump into the jugs, when we get home any left over goes right back into the drum. When the season starts up again, methanol will "clean" the 3.5 gallon fuel cell and fill the 100 micron fuel filter with "cotton". Usually rotate the filter out after two races, then again after two races, then it's good for the balance of the year. Unless we have a super wet spring like this year, then it was every two until the end of May.
