I am considering converting for E85, but I am a little concerned hearing that the composition of E85 may change seasonally to avoid freezing. I live in Texas, where I don't think it's been cold enough to freeze ethanol since the ice age, so in theory they'd not have to change the composition. Do they only do this in colder areas, or everywhere? Is there any way to know other than testing it yourself?

 

They change to E70 for winter here any temps under 50 degrees makes it really hard to start. Stop into one of your local stations that sell E85 they should be able to tell you.

 

you are right, they change it to E70 for winter to help cold starting in cold climates. Im not sure if they would change it in Texas though. Look on the EPAs website maybe.

 

I'm somewhat concerned about this as well, I'm having a e85 conversion done on November 5th so I'm sure that here in Oregon it will be e70. How will I know whent hey change back to e85? How much of a loss in performance am I having from using e70 over e85. kinda bummed

 

So I assume a car tuned on E85 wouldn't run very well or long with E70 in it?

So in essence anyone wanting to run E85 would need two maps?

 

it will run richer with E70 because there is less Ethanol.
Which should be safe, however it may knock with the decreased octane?
If it doesnt knock it should run ok because rich is safe and turbo engines like to go rich.
But yes I think you will need 2 maps.