Ethanol is manufactured as 200 proof, or E100 at the distillery.

This is, for all practical purposes, whisky, and could be digested by humans.

In order to comply with ATF rules, the pure "whisky" must be poisioned, or "denatured" on the premises... no 100% ethanol is allowed to leave the property, or else it would be taxed as a beverage, and cost the same as liquer. ( What does Vodka cost per gallon anyways? $40 a gallon? More? )

So to comply with ATF rules, all ethanol leaves the plant with 2.5% to 5% gasoline in it from the get go. All rail tankers, and all truck tankers are denatured with on average, 4% gasoline.

The gas station then adds 10% of whatever gasoline they have on hand ( probably in most cases the lower Octane ).

The E85 pumps in Minnesota say "contains at least 85% ethanol".

If the ethanol they got this week had 4% denaturant, they would be selling E86 this week. Next week they could get ethanol with the minimum amount of denaturant ( as gas prices rise, this is more likely ) and they could be selling E87.5

I have never ever heard of "winter E70".

-John

P.S. Cars would run fine in warm weather on pure alcohol. Indy cars run on E98, only because they too must have denaturant to comply with ATF. The 15% gasoline is added, mostly, to make it burn easier in cold weather.