Oil Leak Diagnosis: Seals

WARNING: This page is about a different car, the 2010 Chevrolet Aveo. However, it is still accessible from the selected car via links, so may be relevant.

The fluid/pressure is too high.
The crankcase ventilation system is malfunctioning.
The seal bore is damaged, scratched, burred, or nicked.
The seal is damaged or worn.
Improper installation is evident.
There are cracks in the component.
The shaft surface is scratched, nicked, or damaged.
A loose or worn bearing is causing excess seal wear.