Analysis of Leakage
WARNING: This page is about a different car, the 2013 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
Clean the leaking area enough to identify the exact source.
A plugged axle housing vent can cause excessive pinion seal lip wear due to internal pressure buildup.
Verify the lubricant level is at least 3-5 mm (1/8-3/16 in) below the bottom of the fill hole.