My car engine was sound until one morining in april when I started it and it did not pick well. I suspected plug wires and changed. It repeated same problem and I called a mechanic. Not my usual mechanic anyway because I was far from him. The guy interchanged my plug wires (he interchanged number 2 and 3 between engine and distributor)
We did everything and it would not work fine not realising the mistake. Now he opened my engine, grind the two valves concerned and coupled back, yet the problem was still there. We realised the problem later and the car worked fyn but oil in the engine dried up completely after the car was driven for 200kms.
I changed oil and tried again, it still dried after same distance.

My mechanic opened the engine again and told me I have to ring the engine.

My question is if I will not end up wasting scarce resources before coming back to buy engine. Is it really preferable to rebuild engine completely or get another used engine? Advise please.

What make, year and model is your car. I ask because for some engines, it is a waste of time to rebuild when a tokunbo engine would be more cost effective.

Best to buy another engine of the same specification, on the proviso that you get some sort of warranty after replacing.