"Jim Macklin" wrote:
Not necessarily, the oil pressure gauge lines are very small
to prevent a major leak if the line breaks, in cold weather
or just with cold oil, the gauge will respond slower. That
is one of the reasons they say to allow 30 seconds for oil
pressure to show up after a start, it takes some time.

But a stuck relief valve will cause the oil pressure to go
very high instantly and that blows the seals or oil cooler
which drops the pressure before the gauge has time to
respond.

My gauge didn't respond until 5-6 minutes into the flight, but the
cooler obviously split on start-up, as there was a huge puddle there and
another in the run-up area (and no, I had never been taught to look
behind when I pull away to assure there are no puddles, though I sure do
NOW! ... how many pilots that have not had an incident/accident like
this routinely do this?). The oil pressure gauge remained in the normal
position throughout start-up, run-up, takeoff, climb-out and during the
first couple of minutes of cruise; then it read zero pressure.