Covering several points. Before I found this board, I was a long time Pennzoil user, but had little to justify it other than it was a respected brand name and readily available. I am sure there are many other people using it without any hard data to back their choice. It is also appealing to those that figure the most expensive oil must be the best. I have seen enough UOA's and VOA's here to be confident about using it or several cheaper brands. Back when Shell, Quaker State, and Pennzoil were separate companies, the price of Pennzoil reflected the competition. It seems Shell is positioning Pennzoil to exploit those willing to pay top dollar for what they think is the best and those that wish to keep using the same readily available product they always have. For the more price conscious they 2 other brands. They also have a range of synthetics and specialties, SUV, winter formulation, high mileage, etc.
My last oil change tested my loyalty when I ended up paying $18 at Wally's for enough oil. In the end, I decided the other stuff wasn't that much cheaper, and wasn't sure I could find it cheaper than Pennzoil next time, or even find it at all, or at least not without running around a bunch.
Delo or Delvac may be fine oils, attractively priced; but Wally's didn't have anything in stock less than 15W- which is wholly inappropriate for my gasoline engines and moderate short trips.
Bottom line? I am willing to spend extra on a product if I can see a feature that benefits my car or truck. On the other hand, I see no reason to pay a premium for something that is about the same. On filters, if I had my choice of ST, a $3 OEM, Purolator, Hastings, STP, etc., I would take the OEM. Otherwise, ST. I cringe about all the years I was paying a dollar more for a FRAM over ST.