I remember my grandfather yelling about how detergent oil ruined his car.It was a 60 Falcon,and when I took the valve cover off the sludge stood up all on it's own.The valve cover acted like a jello mold.It had been making some noise,and he only had some detergent oil to dump in it.The fact that the engine had been junk for a year had nothing to do with it.It was those two quarts of detergent he was forced to use.The only reason he did use the detergent was because he had run it completely out of oil and had to get home.He said that running it out of oil had nothing to do with it,he had done that dozens of times.It had to be that detergent oil.A few years ago I ordered a barrel of oil to be delivered.They dropped it,and when I wheeled it inside I found it was not 15-40 Rotella,that I'd ordered,but a drum of 40 weight non-detergent.I called them and they were concerned that I might have used some.I told them I had caught it in time and the new barrel was intact.I wheeled it back out and the next day there was a new barrel next to the one going back.When I called them about taking it back they said,we thought you had a waste oil furnace.They didn't even want it back.That was nearly a month's heat for me.