Could the wrong engine oil cause codes P0012, P0022 and P0304?

P0012, p0022, p0304

The oil was changed in the vehicle with something not recommended.

Problems include:
Losing a qt every 3 weeks.
Misfire engine.
(Probably bad coil from possibly getting oil on it).
Loss of power (coil again).
Bad MPGs.
Fuel smell from exhaust.

Other than that, the car starts, drives though I haven't driven it much,

No blue smoke, no thick white smoke, no loud cats (3 on vehicle)

The mechanic said my engine was toast and didn't do anything but pull the 3 codes out of computer. Offered me $1,200.00 for the car which is in excellent condition other than the wrong viscosity oil and bad coil/spark and the 3 trouble codes.

Said timing chain was ruined but there is no sound to indicate bad timing chain and the car starts fine.

The car was driven approximately 2,000 miles in 4 years with the current condition it is in, and the engine hasn't failed and is quiet, but the previous owner kept the oil topped off with that crap too watery like oil.

I want to fix this car and I'm wondering if I even should bother. I don't want a money pit and I cannot afford a new engine or even a new car.