All of your answers make sense. I've wondered about how well those additives mix into the oil and if they accompish what the old oil forumas did. Roller cams are the way to go, for lots of reasons, but if someone is building an old engine, like a flathead, what are they to do?

I remember pulling out the stock cam in my 389 Pontiac, slipping in a 421 cam that we lubed with 50 wt oil and stp, and as soon as we got it running we went for a ride. No breakin procedures, and sometimes we would even let a fresh rebuild sit there and idle for a while, something we now know is a no no. Never had one fail though, which is why I wonder how 50 years later we are now seeing problems we didn't have back then.

Don