Zinc

If you have a stockish cam and valve springs once you have broken them in the ZDDP levels in current SM oils are sufficient. It's big cams with stiff springs that the 800 ppm of current oil is not enough.

BTW, Valvoline VR-1 comes in two flavors SM rated and non rated. In my area all the VR-1 I see on the shelf is SM rated. If it has the SM rating then the ZDDP is down around 800 ppm.