Symptoms: dying oil pump?

[Derick]

So a few around here have been seeing my sporadic posts about my potentially problematic suburban 2500. My 6.0L has about 145k on it. I have seemingly always had lifter noise while in my possession but recently a thunking knock came about. I feel like that is a loose or broken exhaust stay since the exhaust manifolds were replaced.

So anyhow, today a few things started lining up during a short road trip. I've been trying various snake oil treatments, with no change.. Shocker I know... But maybe they are helping at I'm starting to loosen things? I dunno... Anyhow in the past I was getting an indicated ~50 on the oil pressure gauge at startup and speed and about ~30 on idle. Recently, I've been showing 40 at speed and 20ish at idle. Lifter chatter is going pretty good at idle. I feel like things have deteriorated in regards to oil pressure and that might be the source of my problems. Thoughts?

 

[Derick]

Bringing this thread back up since it is related but earlier today I actually recorded some video and wanted to get the community opinion of my oil pressure. Is this falling within expectation? I feel like it's low but I also have no frame of reference and I'm just some guy so what do I know. Let me know what you think.

The beginning is idle, the middle is cruising speed and the last bit is wide open.

 

[Doubeleive]

even with a brand new engine, oil pump and sensor mine does basically the same thing depending on if it's warmed up or not

 

[swathdiver]

Looks like mine.