untill recently there was some benefit due to zinc content, that and the soot control agents amongst others made it a great oil for loose built, high performance engines...
for engines needing to idle alot, or run mid-upper rpm and hot i build the tolerances fat and spec the rotella. now that zinc is down you need to add that for the old school builds i tend to prefer. though i am looking at a napier setup for a planned stroker build i am starting soon, this will be tight and synthetic is in the plan.
older or hi mile 30 wt spec motors wont mind the rotella a bit. anything calling for 5w i would not run it.
