2013 Fiesta Hatchback SE. I have Blackstone analyse the oil after each oil change. I got the following report - There was some fuel present, and 2.5% is a cautionary amount, but some of it could be from operational factors like idling or cold sampling. It does not idle much, and I took the sample hot. I remember getting a recall from Ford about a fuel system defect, but the dealer knows nothing about it. The mileage is a little worse now. What to look for. Any codes related to fuel system. How to fix. No, I do not want to pay the dealer fix it.