My 2002 4.7 Oil Pressure had always stayed dead in the Middle of the Operating Range until About a year or so ago, Then it started to drop to zero suddenly, then come right back up. On some days, it might do it multiple times right in a row and other times, it wouldn't do it at all. I wrote it off as an electrical issue. Now, it's been staying in the middle of the range (pressure good when started) but then it goes to nothing when warms up and it gets below 1,000 RPM. The last time I ran it, it dropped to zero but didn't come back up for 30 seconds or more. I was about 10 miles from home, so I turned around and headed back home (it was about 1:30 in the morning and I figured if it's gonna crater, better to have it closer to the house, since I'd have to go about an hour away to get my Son's car Hauler). I've got it parked right now but am getting a new sending unit and want to put a mechanical gauge on it also. While these gauges with an Operating Range are just barely better than the "Idiot Lights" that used to be in vehicles back when I started driving in the early '70's, nothing beats a GOOD Mechanical Gauge
FWIW, It now has 299,700 miles on it and I've always changed the oil and filter every 3,000 miles or so (I was taught Oil and Filters are cheaper than an Engine, although that may not be true any longer, LOL!).