I am currently having same issue with my 2018 explorer sport 3.5 ecoboost with 47,000 miles on it. Fighting with ford and the dealership with this issue. Of corse every time its at the dealership it will not smoke but every day I start it at home and work it does. It used almost 2qt of oil on a 1600 mile drive. The dealership will not do anything to it unless ford tells them to so they can make sure they get paid. I changed the pcv valve my self and it stopped smoking for about one week and then started doing it again.