Roger that on the diesel spec Rotella oil. I use it and insist that friends use it on all non-roller cam engines. You will always find examples of people who beat the odds, but the zinc conmtent increases your margin of protection during extreme wear conditions, such as cold-start-up. The Zinc content of typical passenger car spec oils has gone down considerably since the 70's. As for royal purple and other synthetics, break your engine in first, then if you want to move to synthetics, fine. Still if you have a non-roller camshaft, use zinc additives or Rotella diesel (hi-zinc) spec oils to be safe. Class racers that must use flat tappets are pretty familiar with this topic.
mv
