[455Grandville]

Originally Posted by ta6point6

Well archoil is supposed to help clean out sludge and has boron to provide more lubrication for less metal to metal friction. If it can clean sludge and provide less friction then theoretically it could improve lubrication hence higher oil pressure.

That sludge will likely pass through a narrow passage and clog it or the oil pump making things worse. Engine machinist love anything that flushes the system as it gives them more business.
If you have low oil pressure drop the pan, take it to a machine shop and have them put it in the parts washer and throw in some new bearings.
Mechanic in a can wont fix excessive bearing clearances.