geez even without oel pressure that exhaust sounds cool
Wish I had a sub woofer connected to this work computer
That gauge does seem screwey especially the way it jumped up by itself during the idle after it intially pressurised. Also the way it didn't respond to the RPM. For piece of mind, take your oil cap off during warm idle, check to see if there's a nice stream of oil coming from the oiler tube on to the cam shaft.
From what I remember of others asking and comparing about oel gauge operation, the needle should move similarly to your 6.9. ie Shoot up to 3 on a cold start and then drop to around 1.5-2 when the oil has warmed and at idle. The pressure goes right back up to 3 again when the revs move up from idle.
So why is the gauge not working? I reckon the line's full of sludge. I don't know but as a guess I reckon a good start apart from checking for leaks is to disconnect the line and flush it. Perhaps undo it near the gauge, place a container under the end
and start the enigne. Observe the oil coming out. It dribbled out of mine at idle. Not a powerful squirt or anything like that but it was free flowing.
Didn't have a problem with my gauge, I just thought it would be a good idea for fresh oil in there after accidentally discovering one day that oil does come out of that line and onto carpets when the engine is running
So next oil change I purged the line. No lumps as such but it was black as. I wonder if thinners or petrol should be squirted into the guage side as well. I didn't bother with that but perhaps should've.