Alvin, you are right about the stovebolt engines not needing much zinc. It has been the new cams and lifters with high spring rates thats eating the cams. A stock 6 cyl with 40 to 50lb valve springs isn't going to need much protection, the EOS GM sells will do the job.
The real problem is the radical cam profiles they are using now, most makers try to get as much lift as fast as they can, so the ramps are really steep. To keep the lifter on the cam, really heavy springs are needed, 200 or more pounds, so now you can start to see why the extra protection is required. A few of the cam makers recommend soft spring for a break in period or at least removing the inner springs.
Dad and I recommend the Brad Penn racing oil (web search for it), our local dyno shop won't run a engine with out it. Its the old Kendell oil reformulated but still a very high zinc content, if not the highest. I also don't like the Rotella's, they are to thick and have a funny smell to them. Thick oils wear the cam/distributor gears to fast and is hard on cold start ups.
This is my opinion, so feel free to throw it out. Joe
