I have just rebuilt (lower end new bearings) this 2000 Volvo S70
in the rebuild i used Volvo main bearings and followed the color codding to the tee.
I am having an oil pressure problem (lack of)
At cold idle the oil pressure is well above 4 bar, and rises and falls w/rpm
eventually the warm idle pressure drops to 2 bar.

and this is when the issues begin
when the idle pressure drops to about 2 bar, the pressure NO longer rises w the RPM. AT ALL, and will eventually get down to less then .5bar STILL not raising w rpm and will eventually go to 0

but what confuses me is when it drops to Zero i immediately shut it down..and upon restart the oil pressure goes back to normal for a couple of minutes at idle, and raising w RPM.

i find it hard to believe that the oil cools down in 2 seconds of a stopped engine to "thicken" up and allow oil pressure to build.

Any ideas?

Thank you and all the best