what are the Common oil leaks? on 2002 Cadillac Seville SLS

My 4.9L northstar leaks oil bad. I tried looking for the leak but there is just oil everywhere. So I figured I would start with the more comon gaskets and work my way from there untill there all changed. I would like to pull the motor and rebuild it but I can't have it off the road for long.

If it's leaking alot of oil daily it's probably your rear main seal.