From my observations of the various MBs in our local club, they all show different oil pressures at idle - some at 1.5, some at 2, etc...mine is at 2.5.
All of them peg at 3 with throttle.
This is correct.
The different oil pressures at idle can be attributed to the different types of oils used, individual engine condition, etc of the individual MB.
As long as the gauge is not pegged at 3 ALL of the time, you are OK.If it does, you probably have a faulty sender.
I use the gauge as a Service Indicator of sorts.Usually when it's time for an oil change, the oil pressure at idle gets lower than usual (in my car, it would be about 2).Then, it's off to the indie for an oil change.