I can confirm that the oil has been very low when I checked it. I actually just asked the mechanic to confirm the repairs. I mentioned that it was expensive and he said that it’s usually 60% less. He’s a mechanic that has serviced two generations in my family. He’s done some basic work for me for free. I trust him.
Since you have a mechanic you can trust, I would just ask him to fix up the car…for exactly those reasons dagosa just mentioned, the primary one being that you love it. The devil you know…and all of that.
I agree with Cig.
Selling (or trading) this for another used car will get you nothing but risk. You love this car, fix it up. Another used car would be a crapshoot. It might end up needing far more than your current car.