Good evening folks, my first post related to my first Duramax engine.
Information:

2007 2500HD with the duramax engine
6.6L engine says it on top of engine cover
Original 26,000 miles on it
On my way home I notice the oil pressure was low I think but don't know?
Cold start 50/55PSI
warm idle 30PSI
30-60mph 35PSI
60-70mph 35-40PSI
80mph 40PSI

Current history:
The oil needs to be changed, the truck sat for months at a time only used in summer to pull large camper.
Any advice related to proper oil pressure will be really appreciated. One last question, what brand oil and filter is a good one to stay with?
Thanks to all, Steve