Subscribing... I noticed the oil pressure in our 05 was on the low side idling too... But while driving, it's up close to 60psi like usual..
20-25 isn't bad idle oil pressure for an LLY. If it's the 05 in your sig, chances are the stepper motor in your cluster is going out. It is a VERY common problem with 03-05 trucks for the steppers in the cluster to start reading off, or just go one way or the other.