With respect to this ZDDP issue and cam lobe failure, I'll pass this nugget along that showed up in a newsletter I get called LSxTV....or something like that. I get like three of them every week.
Anyway, fwiw, they had an article last month discussing oil & ZDDP & cam/lifter failures. I can't remember specifically which boutique oil company participated, but they had an oil company engineer in the discussion along with an engineer from CompCams. Anyway, the main point was that all the agony over the cam wear was due to the blank supplier to CompCams using some bad metal, and not the reduction of the levels of ZDDP to the present levels. This was CompCams' research findings.
I'll go thru their archives and if I find it I'll post a link, okay? In a somewhat related situation. I have a Q about this ZDDP thing in my own mind that I don't have enough knowledge to noodle thru to an answer: What about all the DOHC motors that are in all these economy cars like my Cobalt? Don't they need this ZDDP at the correct levels? I mean even a lot of the V6's are DOHC motors, like the base motor in the stangs & camaros, no? I guess what I don't get is would OEM's be offering these warranties knowing that new oil will cause cam failure? Sorry for my sticking my two cents in here, but something just doesn't add up to me in this whole picture.
Tom