This may add to the controversy:
http://www.cranecams.com/pdf/548e.pdf
I don't recall exactly where I read about the changes in the hardening process but in a recent issue (although it was about roller cams) they talk about their carburizing process on cams taking them to 58-62 'c' on the rockwell scale. Plus they have recently released the Mikronite surface finishing process.
I used to run Mobil 1 5W-30 in my flat tappet motor in the Cobra... until I wiped a lobe. Then I found out about
zinc and have been using Rotella T 5W-40
synthetic but with the new formulations, that may change as well. It has worked great but I have a note into Shell to find out was the new formulation is.
Of course, anyone could just add a bottle of Crane Breakin Lube at
oil changes which has a high concentration of ZDDP. My understanding is that the GM EOS has been discontinued.
There are a number of oils with .11% of
zinc or more (1100 ppm). This is the level I have most heard as the lower threshold. Buy the one you like and be happy!
