ZDDP is one of the things they are taking out of modern motor oil as a concession to emissions control it poisons the cat.
There are still a few oils out there that have high enough ZDDP content to keep the old engines happy like Vavoline VR1 that's what manny run in the MG engines, but then that's just getting happy at 3000 rpm as opposed to a 216 that is topping out in that range.
It's better if the oil has some ZDDP for nonroller style lifters, if you look hard enough you can find oil with some in it.
This is one of those things that comes up form time to time on on forums where you have old style engines.
