Q: Using E-15 fuel in my car do I need to use regular unleaded fuel maybe once in awhile or is it safe to continue to use the E-15?

E-15 is shorthand for gasoline blended with 15% Ethanol which is a fairly corrosive material which can cause damage to rubber parts and other critical parts over time. Ethanol also attracts and bonds with water from the air, and that water can separate out inside the tank due to phase separation. If your vehicle sits for long periods between use, the moisture settles to the bottom of the tank and can potentially clog in-tank pumps and filters. Damage is also possible in fuel lines, injectors, seals, gaskets, and valve seats as well as carburetors on older engines.

The main issue with respect to E-15 in many cases is whether or not the car will be covered under warranty from damage caused by using this product. GM and Ford have certified their own cars starting with 2012 (GM) and 2013 (Ford) to be compatible with E-15 and so some of the newer cars may not have any trouble with this.

I would not recommend using this fuel on longer drives where the chances of burning through an entire tank relatively quickly are greater. This may lessen the chance of excess E-15 fuel sitting in the bottom of your tank for longer periods of time where it may be prone to causing damage as outlined above.

If you run into any issues, feel free to contact YourMechanic, as one of our mobile technicians can come to your home or office to service your vehicle.