No, I would rather buy an oil with the desired ZDDP level than use an additive. This is because each engine oil has a particular additive package already, and mixing in another additive package holds the very real potential to modify the original additives in a way that make them less effective, even to the point of increasing engine wear. That is not to say that some additives won't work well with some particular oils; it is just that we don't usually have any accurate way to know ahead of time how any particular additive will react with a given oil.