I have a racing tune on my 2012 mustang gt which requires 91 or better. I live on Long Island where there is a gas shortage and only regular (87) is available. I uninstalled the tune returning my car to stock. I had to put half a tank of 87 in. Do you think my engine will be ok running on 87?
Yea everyone else nailed it, you'll be safe on stock tune, I wouldn't romp on it though, I don't care that the engine is "able" to use 87 octane, that high of compression really does require 91 or better. Eliminating spark knock by adjusting timing isn't much better for the motor.