P&E SAVVY MAINTENANCE THE PHOTO of Mark's oil filter didn't exhibit anything exciting. 88 | oil pressure at engine start was some sort of foreign matter contaminating the oil pressure relief valve. The pressure relief valve is what regulates engine oil pressure. It's a simple device consisting of a springloaded plunger that is designed to open when oil pressure reaches a certain level (typically about 50 psi for Continentals and 70 psi for Lycomings) to bypass excess pressure from the pump. If foreign matter gets into the pressure relief valve during engine operation and prevents it from closing properly, then at the next startup the idling oil pressure (which is already pretty low) will bypass to the pump inlet and the oil pressure to the engine will be extremely low and might even show zero on the gauge. I suggested that Mark ask the A&P to unscrew the pressure relief valve housing and inspect the valve for contamination. About 30 minutes later, Mark sent me another photo (facing page). I asked Mark to check the tiny chunk of metal with a magnet. He reported that it was nonmagnetic. Given that fact plus the obvious silvery color, I concluded it was almost certainly aluminum (and not bearing material). I told Mark that I was not particularly concerned about this tiny piece of aluminum "unless there are a bunch of its brothers and sisters in the oil sump."http://ciescorp.com