bad pcv valve which on these cars is under the intake manifold which requires removal to access. pcv valve vents crank case pressure and when failed can cause oil to rise and come out of whichever hole it finds first either the dipstick or the cap. pcv valves are cheap but replacement on these models is a royal pain. they are just ball valves but eventually gum up and fail. sometimes open many times closed and you get the symptom you have. do not just clean this part and put it back since replacement is a pain buy a new one! on most cars the pcv valve is on top of the motor but for some odd reason FORD decided they knew better (ford had too many hands on these motors) the new skyactivs are far superior, I owned 2 non skyactiv 3s 08 and 11 and both had the ford labeled parts or systems have issues.