The other day when I was driving down the highway noticed that my oil pressure gauge in my cluster was moving around a lot never to zero but would fluctuate between 25-40 psi. Slowed down and sped back up again and it stayed right around 40 and didn't move anymore. Figured I would get a more reliable mechanical gauge and install. I used the port on top of the oil filter housing and ran my line into the cab to the gauge it ended up being close to 12 feet of line to keep it away from the heat on the hot side of the engine. Started the truck up and it seemed to work good until it started to read about 25 psi then the gauge started to skip up like it was sticking. It finished at about 52 psi and would stay there unless I bumped the throttle got it up to 62 psi and it wouldn't go up or down. Shut the truck off and it takes a long time for it to drop back to zero. Any ideas?

 

I would try a different guage

 

Sounds like a restriction or debris in the line or gauge.
I would check for kinks in the line.

 

i think you have an oil pressure problem since it is acting up with the oem gauge as well as the manual gauge

 

Went back and looked at the entire line there was no kinks but took apart my union just before the cab and found that one of the compression fittings went in a little bit crooked and was cutting the line off removed the damaged portion of the line installed new fittings and fired the truck up. Works good now when running but still takes quite a while for the pressure to drop to zero when I shut off the truck. Drops really fast to about 20 psi then slows down.