how the hell

If you lost oil pressure (post #6), you should have seen the oil warning lamp light. It should light when you first turn the key to IGN, before you crank, as a "lamp check". If you haven't been seeing that, you have been living dangerously. Also, the oil pickup screen can clog. I think that was the problem my mom had when I was a kid, driving our ~1963 Valiant wagon, in ~1969. She proved that a slant will go 4 miles w/o oil and then seize forever. But, people thought 6 yrs out a car was great back then. We have become smarter.