I've done lots of reading on oils and additives and the conclusion I come to is once a flat tappet cam and lifters are broken in, you can run a standard off the shelf oil and not the high zinc stuff. As has been stated in this thread, ALL motor oil has ZDDP. It has to. It's my opinion, wrong right or otherwise that once a cam and lifters are broken in the extra ZDDP is no longer required......but I still run some anyway for good measure.