So been reading up on this problem and had the shop Chang the oil using the correct oil filter. Change the psi sender. Change filter in the psi sender. 50 pds psi! For about 20 minutes, then psi started dropping again. Up and down. No engine noise and runs fine.
what else could it be?

 

Welcome to Chevy
Please list your cold psi reading at idle and cold psi at 2000; then warmed psi at idle and 2000 rpm. What weight oil in use?
Also, are you blowing any smoke; what's your rate of oil consumption.

 

Oil psi code is 50psi cold. Then drops to 20, to 0, then 20, then maybe 50, the 0.
no smoke. No noise.

 

I would question the accuracy of your guage and or sender with those fluctuations

 

Would a one day old sender go bad? Or so much junk inside the crankcase clogging up the sender filter that fast?

 

Could be the gauge and not the sender. Can hook up a mechanical gauge to verify true pressures. I'll bet there's a way to test the sender as well - hopefully those smarter than me will chime in with more info.

 

But the alarm goes off when it drops below (whatever the threshold is) so sounds like either stopping up again, pos new sensor, short in the wiring harness, or bad o-ring on the oil pump pick up tube.

 

A diagnostic scan tool, probably

 

Unfortunately, The scan tool only reads the value of the sender.
My employee said it seems to be stabilizing now around 20 lbs. No alarms. Maybe we should pull the pos battery cable again now, I saw a Youtube video where they said that has to be does to reset everything.

 

Right, which would rule out the gauge.