Low Oil pressure when hot

[Ra1994gh]

Sorry for the late reply but I did not have the chance to work with the car before today. So I changed the oil filter with a MAN filter, changed oil to 20w-50 and installed the manual gauge and on cold start idle the pressure rises to 30 psi quickly. As the oil gets hotter the pressure drops and it drops all the way down to 1-2 psi fully warm. And 2000 rpm roughly 10 psi and 3000 rpm around 20 psi. I am starting to think that either main bearings or rod bearings may be my issue or both. What should be my next move? Can I inspect them or change them by only getting the sump off while still having the block installed?
and what should I look for?

[digger]

That doesnt seem good at all.

Thinking out loud you might get lucky if you can pull the pan and check the pump, the separate relief valve and even the rod bearing clearance with plastigauge in situ.

Checking the mains in situ is not as accurate in the car but can work around that but if they are the issue its an engine out job whereas the other stuff potentially in car / in situ replacement may work depending on the root cause and consequential damage if any.

The intermediate shaft bearings can be checked by removing the belt etc and feeling for play or measuring with dial indicator and/or removing of the shaft to measure bearings in situ if you have a small gauge