What oil has zinc now?

Axe is right. Viscosity modifiers, seal conditioners, etc, all reduce the lubricity of the oil itself. Back in the day (early eighties) Crane used to recommend straight weight oil for cam break-in for just this reason.

The problem is that the high pressure additives that used to be in oil (zinc phosphates) have been reduced to prevent catalytic converter failure in older cars that burn some oil.

I used the Hughes additive on engine break-in and the subsequent oil change. Now that it's winter here (it was 9 F this morning) I have switched out to 10W-40 with no additive. Cam hasn't puked yet in over 300 miles since swapping oils.