I have no doubt that there were many excellent motor oils available that were engineered for our engines when our cars were new. The engines are now engineered differently, overhead cam or roller cam vs. flat tappet. Oils are engineered differently as well. EPA regs cut the phosphorus level in oil to reduce emissions, which meant removing ZDDP.

Diesel rated oils do not yet have to meet the spec. Rotella is still friendly, but the picture is changing.

Some racing oils have ZDDP content as well, but at a higher price than Rotella T. Be certain that your Rotella T is the CJ-3 spec, not the new CJ-4. ZDDP is gone as of October when the switch to CJ-4 is mandated, even in diesel oils, so either stock up now or plan to switch to a racing oil or add one pint of STP Oil Treatment at every oil change to any API or CJ spec motor oil. STP has 1% - 5% zinc compounds.