Sorry for the delayed response
The reason I use Penzoil is mostly habit, my father used it and I've just kept using it and have had good luck with it. It is a high parifin oil that just got a bad reputation, but parifin is a good lubricant. Changing it often is more important because of that and the high detergent diesel variant helps keep everything in suspension to be drained out when you change the oil hot and change the oil often. When I first needed diesel oil all oils had a "C" rating so I stuck with Penzoil. A few years ago I noticed that changed and I had to go out of my to find it and it became named "Long Life". The reason I've stayed with is that from an engine class I took a while ago I was told you shouldn't mix oil brands cause they may not get along. I've since heard reseach that oil brands are pretty much the same so I've just stayed with them. I also use the diesel oil in all my engines, diesel oil is gas oil but better. My wife has very harsh driving, she drives five miniutes to the train station, and my motorcycle only gets ridden once in a blue moon, until my daughter can reach the foot pegs. So I'll just stay with this oil.