I just recently switched from PP back to Pennzoil conventional for our vehicles and they all sound/run fine. Since I usually go by the OLM in our Chevy vehicles which often goes around 5,000 miles anyway, the conventional oil works out great. Considering Pennzoil is the pretty much the only thing our family has ever used, I guess you could say we are fans of it. I works for us, so I see no need to change. My 2 cents......