Zleviticus, you've hit on it exactly. Most of what you see in the whole zinc additivve business is snake oil. They overexagerate the issues to make it look like there's an actual problem, when it really isn't. Now that's not to say there hasn't ben cam failure issues, but most of them fall under the following catagories; Incorrect assembly; Incorrectly matched or improper parts (race springs on a street cam, for example); Poor quality/defective parts; Improper break in procedure.
If you use a good quality motor oil, you'll be fine. Also, I would advise against using a Deisel grade oil, especially in an engine that's already been run on gas engine spec oil due to the hihger amount of detergent in Deisel spec. It'll clean everything out of the pan and crankase, potentially risking plugging up oil galleries, as well as clearing out any varnish buildup on the seals, making the leak.
