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A recent article in Hot Rod addressed this same issue. The article stated that Shell Rotella T 15w-40 (made primarily for diesel engines) still had the additives needed for camshaft/lifter break in for rebuilt engines. Personally-I use Rotella T in everything I own-from my John Deere, '66 Dart, etc. My 96 Concorde which we purchased new has had Rotella in it since I first got it home-it now has 211,000 + miles on it-still runs great and uses absolutely no oil.
Todd
I jumped on the Rotella bandwagon after Mobil-1 Extended Performance got emasculated with the API SM limits on additives (it used to be that M1 Extended still had the SL rating, while "regular" M1 got the SM, but that's no longer the case). Todd
Unfortunately, it is ALSO no longer the case that Rotella T 15w-40 has an SL rating. Its gone to SM as well, and what's worse it lost its CI-4plus rating and is now rated CJ-4
Shell Rotalla Synthetic 5w40, at least the bottles still on shelves at the stores I checked, is still rated CI-4plus, so buy in quantity while you can. If you can live with a conventional oil with a 15-40 rating (I don't want to waste that much power, and with a high-volume oil pump in a v8 you don't have to worry about stripping the drive gear) then you can still get Chevron Delo400 and Mobil Delvac 1300 with a CI-4 plus rating. Mobil Devlac1 5w40 is a synthetic that also meets CI-4 plus and API SL (not SM, which is the "bad" one for flat-cam engines).
But the bottom line is that ALL oils, including the "good" diesel oils like Rotella, Delvac, and Delo, are all going to get their zinc levels reduced in coming years. The good (sorta) news is that the diesel oils will probably continue to have better cam protection since there are still a whole lot of flat-tappet diesels out there in the wild that need protection, even if they have to do it with other additives than ZDDP. The "better" news is that the whole issue is probably not that much of an issue with stock cams. Its the high-lift, high-rate cams that have to run monster valve springs that see the real problems. And there are other things being worked too. At least one lifter manufacturer is now drilling a small oiling hole right on the cam contact face of the lifter to greatly increase the amount of oil film available. Plus "beehive" springs are becoming more popular because they're much easier on cams.