Hey guys I did spark plugs in my dads 5.0 yesterday and after the plugs I noticed it started knocking(more like ticking) .He also powerwashed the engine while it was runing not sure if that made any differnece. He runs 5W20 Valvoline Conventional. I took a stethoscope from my emt class and pinpointed the sound. It came right at the center of the oil pan(right above it). Im not sure what it could be.

Here is the thing about the car. It has 120K miles on it. I used NGK T55 plugs and I found out that when the car was borrowed by my uncle plugs werent changed for 80K miles. They looked okay,just worn out ready to go out.


What could it be??

 

And every time the car is turned off I hear oil draining back into the pan. Not sure if thats normal with the pushrod 5.0s.