Hi:
I have a 2010 MGM flex fuel. It runs great on E85, but there is only station with only one E85 pump in town. If I take a trip of several hundred miles, I will have to fill up with regular gas to get back. Also, the ethanol pump is sometimes not available so the only alternative is to use regular gas. I note that the owner's manual says that you should use ethanol or regular and should refrain from mixing them. Also, it says that you should not add less than 5 gallons of ethanol at one time; you should wait until the tank is nearly empty before filling up with E85. After that, you must drive 5 miles when switching from one fuel to the other in order to give the car's computers time to adjust.
I would like to use ethanol and regular gas interchangeably but I don't want to damage the car. I note that GM says that you can use any combination of E85 and gasoline. When I worked for the state, they had a fleet of flex fuel impalas and they told us to use ethanol as much as possible and that there was no problem mixing it with gasoline. I contacted Ford for advice and they simply quoted the owner's manual.
So, my question is - do you think it would be safe to simply fill up with ethanol and gasoline depending on which pump is available and where I am going? Thanks.

 

I know this is late as I have been away a while.
Any combination is ok as the ECM can sort it out. Personally I don't like E- 85 because of the reduced mpg over regular gasoline. My Mercury dropped from 29 mpg to 23 when I used E-85. So I stick to regular gas. Now if they would drop the E-85 price per gallon so it would be cheaper per mile, then I would use it when I can. That is darn few times tho because I have only found it in the mid west, & I live on the west coast.

 

Thanks for your reply. Yes, I too have switched to regular gas because the price differential between E85 and gasoline makes it uneconomical to use E85. I live in upstate NY and ethanol is less than 40 cents per gallon cheaper than gasoline.