Also, don't mistake me for a car expert. I have no idea what I'm doing. I just want to scream about what the results my research and troubleshooting have given me.

A very important rear main valve seal (which is like a 10 hour job for an experienced mechanic, from what I understand?) before I would accept defeat and the underwhelming trade-in value.

Basically more uncertainty whether I'll be able to actually fix my car, or whether it wouldn't even be worth it. However, I currently don't have a job and can't exactly afford a new one, so there's a good chance I would try - and likely fail - to dismantle the engine/transmission enough to replace

If you don't mind me asking, what is it about the terminator lines for shadows that you don't like?