Used Motor Oil Settles

Yep, same here.
I had a bad experience back around the mid-80s with a car that suffered a seized cam shaft. Upon disassembly, the oil sludge was surprising. Lots of waxy like consistency deposits throughout. I was using Pennzoil in everything at the time and decided to switch. Never even considered trying it again after that. Still will not. Exactly as Bing described…