Congrats on your new(ish) airplane.
Unless it’s been modified, the oil pressure gauge is what’s called a direct reading gauge. That means a tiny copper tube is connected to a fitting (with a restrictor so if there’s a leak all the oil won’t be pumped out immediately) on the engine. This tube is connected to the oil pressure gauge.
Sometimes, especially when out side air temperatures get colder, the OP indication is slow to come up due to “thick” oil or because the capillary tube is gummed up.
This can be over come by carefully disconnecting the tube on the back of the gauge and, using air pressure blowing into the tube to push the thick oil or crud in the tube out at the engine end.
If you’re really enterprising, you can disconnect the capillary tube at the engine end to prevent the “crud” from being blown back into the engine.
Reconnect both ends of the tube; the line should self bleed to remove air.
If you have an electronic engine monitor, the cause is most often corrosion on one of the wire terminals on the wiring, a broken wire or a bad sender unit.
Let me know what you discover.
Steve
