2001 5.2 318 . Oil pressure gauge 45 psi, dropping down to 20-30 psi, than at times to o psi. replaced sending unit, same problem. No noise from engine when oil psi reads 0 psi. Any ideas? I have heard that older 5.2 engines are know for the oil pump screen to clog up and restrict flow. I was told to take off oil filter and blow compressed air unto filter housing using an adapter in place of the filter

 

Ive heard of fixing that sender is supposed to fix the issue.
The pumps are known to get weak, but I would try thicker oil too.
Id like to know this issue if I ever have this issue. Hopefully someone else can add more

 

first thing I would do is connect a mechanical gauge and see what your oil pressure really is.... I had a sending unit go bad in one of my ram trucks 5 or 10 years ago... it happens...

 

Has a new sending unit, i put in a mechanical gage today. I put sea foam in oil 50 miles ago, seems to be better.I am thinking its carbon blocking oil intake to pump.

 

UPDATE - 150 miles with Sea Foam in oil. No problems with oil pressure yet

 

UPDATE - 200 miles, oil 40 psi ,, exited freeway , now doing 35 mph, oil drops to 20 psi and stays there. Increased speed to 50, oil still at 18-20 psi. Drove for about 4 miles pulled over and turned off engine, restarted ,, oil psi back to normal. Third time its done this in couple weeks.I am thinking oil pump relief staying open , not closing, to increase pressure

 

UPDATE ,,,poured in Seafoam oil treatment and still had problem after 300 miles,,, removed oil pan and the oil pump intake screen was almost completely restricted with a hard black carbon,, installed new pump & intake tube/screen, all good back to normal oil pressure. 115,000 miles on engine,,,new oil & filter every 6000 miles with Valvoline Syn 10W30 & Mobil one filter