4 1/2 or 5 quarts of oil with 1/2 quart of ZZDP?

For a lot of reasons, additives aren't a good idea. Buy a fully formulated oil that has what you need in it already. If you're done breaking it in, this has all the ZDDP you need at a good price. It's one of the best deals out there for our cars.
Robot or human?