Changed oil put in Valvoline Premium Blue Extreme 5W40 and Mopar filter. Now on starup oil pressure will stay on the hash mark that is past 40 until engine temp starts to rise then oil pressure will slowly drop to 40 while driving. Sometime after engine is hot pressure will drop below 40 while idleing. I have read that the guage isn't very accurate. Is this anything to worry about.

 

The gauge is pre-programmed on what to read. It is only going to tell you when pressure drops below 6psi from what I remember. To get an accurate reading, install a oil pressure gauge.

 

Sounds normal to me for the factory gauge. First start up of the day and my "real" oil pressure gauge shows almost 100psi upon takeoff until the oil heats up and thins out.....after that idle is 25psi and cruise runs upwards of 75psi.

 

New oil will show higher pressure, as well as cold oil- first startups.
It sounds normal to me. If it had gone real high, that would be one thing. A little above 40 is no problem.

 

As Spooler mentioned, the in-dash oil pressure gauge in 2003+ Dodge Cummins is a fake. Completely ignore it unless the warning light is on.