Not really sure where to put this, not to mention I'm on my phone ATM so I can't see all the boards. Anyway, I have a 2014 Focus ST 646 miles. I just out gas treatment (STP) and marathon gas on my car. I filled it up. Now when I'm driving the mpg monitor is going insane up and down like by the second. Did I do some thing wrong? What should I do? The car seems to be driving just fine.