about the only thing in the engine i could see caring about the the oil or what is in the oil is a flat tappet cam. i really don't see bearings in a engine really caring about what oil they get as long as they keep getting oil. i find most of the time if a engine burns or leaks enough oil most of the time eventually the owner stops checking the oil level as often as they should and runs it low or out of oil and has the engine fail whether they want to admit it or not. i know my dad has told me stories of some vehicles that he had that would go though a gallon or more of oil a month but oil was cheap and so was the vehicles so he never care

 

Depending on the engine, some engines really are picky about oil. Later engines with smaller displacement get worked really hard. If you consider the internal environment in the engine, the reciprocating masses put a lot of strain on components. Rotating forces are less stressful but still a lot of heat is removed by that thin film flowing on a bearing as well as holding the metal apart. When I first started driving a truck mumbledemumble years ago, we'd use the green bulk oil in glass jars. Engines back then had fairly loose tolerances. If I have an engine leaking oil, I'll eventually track down the leak and fix it. If it's a skeeter beater, I keep an eye on it. One reason I've looked several times at new vehicles but not bought one was the lack of a dip stick on the transmission. Checking engine and transmission oil was the first thing I learned when I started driving.