Tom, others here disagree, but I would never add ZDDP or ZDDPlus to motor oil. Having too much zinc and phosphorus is just as bad as not having enough - it will plate out on the bearing surfaces with high pressure and destroy your machined surfaces. Instead I would use Brad Penn's oil, which has a full measure of ZDDP in the formula, or Joe Gibbs Racing Oil which is the same. There are some other "startup" oils out there, but for me I would not be dumping additives into the mix. Just my $0.02.