Mobil says 1000ppm for the 5-40 and 1200/1300 for the 15-50. It WILL be fine in the Caddy but I wouldn't trust it in any of the really hot muscle cars with way high spring pressures or a super built hot rod. I could be wrong, of course. 1500ppm and up was what the oils of yesteryear had.
I do believe there are other wear additives in the 5-40 though becuase it says on the bottle that it is CI-4+, CJ-4+ and SL approved. Which surprised me. I thought all those certifications carried a much higher ZDDP level.
I read it was a very robust oil with a great add pack so I figured I would give it a try.