“Well oiled is wonderful.
Well deposited (at a later date) is a future appointment with a bank account disaster.
Are you saying Castrol oils cause sludge or deposits? That’s not been my experience and I use both a lot.
Here’s my old M54 with 110k miles on it when it took a valve cover gasket. Continued to 160k before selling it.
Have run 0w40 my (3) gen 1 3.5 Ecoboost, 2 Mazdaspeed3s and the wife ‘17 Expedition.
My gen 2 3.5 will get Magnatec 5w30 because of the UOAs here. Member KJSmith has several that don’t seem to indicate deposits or sludge, just low wear #s