[Bob Mulry]

I'll just throw my 2 cents in.....

A few more points of internal engine oil leakage are the rod side clearance, if the rear main has had the split chamfered for more oiling to the thrust faces, cam bearing clearance, seal between the oil pump mounting surface and the cap, oil pump body to cover leakage and gear end play.....

Do you monitor the oil pressure at the front of the block or the rear?

A bad oil filter bypass valve doesn't vent to the pan it just bypasses the filter...