Hey guys I have an 04 MT with 140k miles on the original motor. The car runs fine, has never had a CEL in my time of ownership, but I have a few concerns.

First off, I just changed my oil 300 miles ago and when I check it, it doesn't seem to have dropped in level at all. Also, there's a little bit of oil that seems to be leaking from around the middle of the cat. I haven't been able to figure out where it's coming from exactly, but my guess Is maybe the oil pan. Anyway, just looking for a way to figure out my oil burning issue. Does anyone have a write up on how to check the MOP lines, injectors, etc? I tried to find one but I could not. Any help is appreciated.