Sometimes the Hydraulic lash adjusters can have problems also, you can get repair kits or replace them fairly cheaply I think but some labour involved. Certainly not as much as pulling out the engine and replacing the gasketsnot ford said:My engine used to tap. I pulled the motor out then changed all the gaskets to stop all the oil leaks. It doesn't tap at all anymore and I still use the same oil, Penrite HPR15.
I don't know what I did but from that I would assume that the oil is not the true fix (unless you are reusing old sump oil or the like) or the problem.