4.3 Tbi oil pressure

I have a 94 k1500 with a 4.3 v6. After driving the truck for about 15 minutes the oil pressure gauge goes in to the red. No light comes on, ever. If I blip the throttle oil pressure on the gauge comes back up to around 10 psi and stays there until I drive another 15 minutes or so. The engine never makes any unusual noise, sounds tight.
BTW, oil pressure sender was replaced a few months back but on fixed the problem teporarily.
Any ideas? Thanks.

I have a 94 k1500 with a 4.3 v6. After driving the truck for about 15 minutes the oil pressure gauge goes in to the red. No light comes on, ever. If I blip the throttle oil pressure on the gauge comes back up to around 10 psi and stays there until I drive another 15 minutes or so. The engine never makes any unusual noise, sounds tight.
BTW, oil pressure sender was replaced a few months back but on fixed the problem teporarily.
Any ideas? Thanks.

You need to start by putting/hooking up a manual oil pressure test gauge on it and check good engine oil pressure.

Post back pressure readings cold and hot at idle and at 2 -3 K rpm

When I went home last night I poured a little Sea Foam in the crankcase and let it run for a few minutes. I haven't had this truck very long, but when I got it I could tell right off that it had been neglected it's whole life. I changed the oil and put in Valvoline 10W-40. Readings on the guage in the dash are back to normal. I'm still going to put a mechanical guage on the truck and watch it for a day or two just to see what it's doing.

When I went home last night I poured a little Sea Foam in the crankcase and let it run for a few minutes. I haven't had this truck very long, but when I got it I could tell right off that it had been neglected it's whole life. I changed the oil and put in Valvoline 10W-40. Readings on the guage in the dash are back to normal. I'm still going to put a mechanical guage on the truck and watch it for a day or two just to see what it's doing.

Sea Foam in crankcase can do more harm than good.

It's done now, lol!
Pouring a solvent in the crankcase was a last resort for me, and typically I wouldn't do it, but in this case I just thought I would try. It could have gone the other way and bit the dust by doing that and in a hurry too. This isn't a daily driver though, just a project, so I take risks with it that I wouldn't take with a daily driver. I just want this motor to hold together long enough for me to source more parts for my Cummins 4bt swap.

I'd first verify that the gauge is working but installing a mechanical gauge, however if the motor has been neglected, the gauge is probably not the problem. If the motor is trashed, throw in as many chemicals as you want.

After the oil change and flush with Sea Foam, the oil pressure guage hasn't fluctuated or dropped into the red. You usually don't get that lucky. The engine holds around 12 psi at idle even after warm now (I did get to put a mechanical guage on it). I decided to drive the truck around, so far so good.