The 2.7 Ecoboost uses a composite (plastic) oil pan. It uses a 1/4 turn plastic drain plug that seals with an o-ring.Plastic drain plug? For what?
Some say to replace them from time to time. I imagine you could replace the o-ring. A visual check for an oil soiled pan lets you know it is time to replace. My guess is, it's a good idea to have a spare on hand...