Low oil pressure at 2.8 / V6

.. who has experience with oil pressure. My machine (2.8/V6/AAH/’94/300tkm) worries me slowly. When starting, after a day of standstill, the engine noises very strongly in idle mode and the oil lamp burns; the oil pressure indicator is zero. This condition changes only by increasing the speed to approx. 2000rpm, then both disappears. In warm condition this does not occur. I then tested with the gas pedal at different speeds as follows. n Condition the values: – Idle speed approx. 1.8bar – 1500rpm approx. 3.0bar – starting from 2200rpm approx. 4.8 bar – constant to full throttle. I am aware that the display is inaccurate; but shows how the pressure course is at different speeds. What are the experience values for this machine? I believe the 2.6/V6 was built in a similar way. The whole vehicle is with 300tkm in an impeccable condition and I don’t want to let it break … Thanks for a tip. Greetings Andy