Drive Pinion Nut
WARNING: This page is about a different car, the 2018 Ford Focus. However, it is still accessible from the selected car via links, so may be relevant.
On some high-mileage vehicles, oil may leak through the threads of the drive pinion nut. Replace the drive pinion nut as necessary. For information on replacing the drive pinion nut, REFER to: Drive Pinion Flange .