Oil pressure concerns

66 Valiant wagon said
This isn't an A body but I have a 1999 Jeep TJ with a hydraulic flat tappet 4 cylinder. I've had it since it had 28,000 miles and it now has 210,000. I've always just run a synthetic blend and have never added any extra ZDDP. I'm commenting because I am convinced that once the cam is broken in there isn't any need for extra additives. I know alot of my fellow Jeepers out there are convinced they do need the extra ZDDP but I guess my engine is proof they don't.
I don't add any my older engines either and I don't have any problems.
Just my $0.02

For a stock 318, you're probably right. In 1999, when your Jeep was built, ILSAC GF2 was already in effect, which reduced the amount of Phosphorous to 1000 ppm, I think. Chrysler was is part of ILSAC, which came up with this reduction in order to preserve catalytic converter health, which were federally mandated to be warranted much longer than the rest of the vehicle.