There are lots of oils with high ZDDP. Excessive ZDDP will 'poison' the cats. So 'more is better' has limits.For example, Mobil 1 5-40"Turbo Diesel"has more ZDDP than regular Mobil 1.
The question is the balance in the additive package.
I linked an old comparative list some time ago from BITOG for film strength and ZDDP. Motorcraft 5-50 was surprisingly good in that comparison JGibbs was included in the list.
But there is way more to the issue than just two factors in the additive package.
11. 5W50 Castrol Edge with Syntec API SN, synthetic, formerly Castrol Syntec, black bottle = 75,409 psi
zinc = 1252 ppm
phos = 1197 ppm
ZDDP = 1200 ppm
8. 10W30 Joe Gibbs HR4 Hotrod Oil synthetic = 86,270 psi
zinc = 1247 ppm
phos = 1137 ppm
ZDDP = 1100 ppm
3. 10W30 Valvoline VR1 Conventional Racing Oil (silver bottle) = 103,505 psi
zinc = 1472 ppm
phos = 1544 ppm
ZDDP = 1500 ppm
For the oil Geeks only:
http://speedtalk.com/forum/viewtopic.php?f=1&t=35836
http://www.intellidog.com/dieselmann/powers~1.htm
http://www.machinerylubrication.com/Read/255/oil-foam
http://www.bobistheoilguy.com/motor-oil-101/