Can e85 be mixed with regular gasoline?
This question is asked very often. Since e85 is already a mixture of 85 percent ethanol and 15 percent gasoline, it is just fine to mix the two fuels.
Let’s say that you fill up with e85 before a trip then continue to your destination. When you are ready to leave, you notice there are no e85 stations around. You have less then half a tank left of e85, and you need to fill up. Filling up your tank with regular gas is just fine for your flex fuel vehicle.
Filling up will regular gas will only dilute the e85 ethanol from the original fill up. With a rough calculation, if you have half a tank of e85 and fill up with regular gas, you will have approximately 40 percent ethanol and 60 percent gasoline in your tank.
If your vehicle is a flex fuel vehicle, it will be able to take any combination of e85 and gasoline.