What's the best engine oil for a flat tappet cam.

[Street Fighter]

I have several old school cars and I have heard that zinc and other additives have been removed from engine oils,All of the cars have less than 20,000 miles on them so I want a good oil that will keep them running for a long time.what oil have some of you found really makes a difference in none roller cam engines?

[Silverbird01]

I have had great results using Shell Rotella 15w40 in my 67 Pontiac GTO with a 400ci. It's considered a HD diesel oil but does still have the minimum recommended additives that these engines need.

[Street Fighter]

I have had great results using Shell Rotella 15w40 in my 67 Pontiac GTO with a 400ci. It's considered a HD diesel oil but does still have the minimum recommended additives that these engines need.

That's the oil that I have been using in my cars and had never had a problem until this week,I have to replace the cam and lifters, I can't say that it came from using the Rotella because I rebuilt the engine about 13 years ago. I use it in all of my cars and not one problem until now.I feel that it was something I my not have done when breaking in the engine.I plan on staying with the Rotella until I hear of something better.I was a diesel mechanic until I retired 6 months ago,Rotella was what we used in all of our trucks big and small.thanks for the OK on this oil I was wondering if I was the only one using it.