Dont worry about low oil pressure. As the oil warms up, the oil exapnds and thins out. In my 99 S420, my oil pressure was around 1 at idle so Mercedes changed the oil pump and sending unit. At startup the oil pressure shoots up but it then slowly decreases as it warms up. I was told it is normal.
Like me, I see you're in So. Cal., using a heavier weight oil will prolong the oil pressure but eventually it will thin out. I have a 300E, and I used 5 bottles of Chevron 20W-50 and 1 bottle of Mobil 1 10W/30 w/ a Mobil filter. During short trips for 15 min, the lowest I read is 2 bar but after traffic of the 101-405, it goes down to 1. If you oil pressure does not jump to 3 during acceleration, then you might have a problem or you need an oil change. Relax