1996 7.3 oil pressure gauge jumping

[Milligan96350]

Hey Guys got a little issue that's driving me crazy,
Oil pressure needle goes to low and then jumps to normal and back to low again after about 15 min on interstate the pressure drops when I come to a stop and truck goes to idle then it will flicker.. you can cut truck off and it starts right back .. replaced sending unit didn't fix but it seems as when the oil cools back down it dosent do it anymore.. running Rotella 15/40

Thanks for any help

 

[Magnum PD]

May want to get a mechanical gauge and see what's it doing. LPOP may be going out.

 

[6.0 Tech]

^ this. I had one about 6 months back that someone had reseed a pan on and a bunch of silicone was plugging up the pickup. Took out the bearings. That one would idle with the gauge good cold, but when hot only had 3 psi, and revving it to 2000 had 0.

 

[Blumkin]

The gauge on obs truck is really idiot light once it reads 7psi or something it comes on a reads normal no real indication. Obviously heui truck won't run without oil pressure. Check oil pressure with mechanical gauge at hpop resevoir or oil filter housing. Also after a good romping pull dipstick check for foam. Oil pressure should be above 10 or 12 hot idle and above 40 at 3000rpm hot