I certainly think having a qualified tech look at it is wise.

And I have heard a way to tell if rods are knocking is to rev engine to 2K rpm in neutral and modulate the gas so the tach rocks back and forth by the 2000 rpm mark buy a few hundred rpm each way. Listen for the knock.

Listening to another C230 is a good idea.

I have a C230 and it is a engine with lots of little noises coming from the head. always has been and I run 0W40 Mobil 1 synthetic since available and synthetic from 1600 miles when new.

also with pinging from off timed combustion you'll notice it most under load when hitting a hill and the rpm are low - to high a gear on a hill.