it was quaker state around here as well. pennzoil had a good rep.
of course long spans between changes, only changing the filter every other oil change, short trips not getting the engine up to temperature, plugged up breather systems, all contributed to the engine pics Barry posted. it didn't matter what oil was used. i got many engines like that back in my junkyard ownership days.
guys used to "unsludge" engines by draining the oil out, then dumping in 5 or 6 quarts of diesel fuel or kerosene, running the thing for "x" amount of time, draining the stuff, then adding new oil.