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
