Ok, here's the deal my 97 540i with 160K has indicated that it has lost oil pressure 3 times in the last year. It happens after a quick throttle blip (rpm up to about 3 or 4k), warm engine. The first time I shut down, check oil, level good, restart still no pressure indication (no lifter racket though like you would think with no oil pressure). Dealer diagnosed next day as bad pressure switch. No problems for several months. Then happened again about 4 weeks ago, same way, I left car overnight in parking lot (afraid to move) went back with flatbed and just to see, started car. Oil pressure ok. Took home on flatbed and replaced pressure switch and dropped lower oil pan to make sure oil pump bolts tight. All three bolts in place and tight. 2 days ago same thing happens after another blip on throttle. I'm thinking, can't be another switch. In between incidents there have been plenty of full throttle excursions to the redline when going places. But those didn't result in loss of pressure indication. Anyone with any suggestions? Maybe an overpressure bypass that is lifting and not reseating (engineer speculation). Thanks for reading the long post and for any suggestions.