so i go to the dealer to get a oil change and i ask the guy thats working at the desk about flex fuel ,because i was going to fill up after the oil change... so he tells me that i have to fill up with the tank on empty( i still had a half a tank) and then he starts saying how bad it is and everything else..... so i go to the gas station and start filling up with just reg gas... while im filling up sum guy come over and start asking me about my truck and why im not using the flex fuel.... he tells me that hes a retire mechanic and as soon as my truck gets down to a half a tank use the e85.. then when that gets down to a half go back to reg,he says my truck will run alot better and that the e 85 was 45 cents cheaper.... i do know running the e85 the gas millage is worst but i was just wondering if anybody has tryed alternating the fuels like this

 

e85 gets worse gas mileage so its really not worth it

 

If I remember correctly.....you can fill up with e85 anytime on a flex fuel vehicle...your tank doesn't need to be empty to do this...the computer will sample the fuel mixture and go from there....

As far as the mechanic saying e85 is hard on stuff..I would hope all the components are engineered not to degrade due to the ethanol being corrosive...

 

The owners manual states to switch fuels with no more than 1/2 tank. You do not need to be on empty. Yes your fuel mileage will suffer, mine is usually at least 2 mpg. I did find that if I slowed down abit on the highway, I could get some of that mpg back.