The type of oil used and how long the car has been running can dictate the oil pressure at idle. So if you use synthetic and have been driving for a few hours it will be pretty low (around 1 on my car anyway) but if you are using dino oil it will be up a bit and if you have been driving or idling for less than 30 or so minutes it stays up there in the 2-3 range until the car really gets going for bit.