low to no oil pressure

[86RangerMan]

Hello, wanted to ask, what could be the possible cause for my oil pressure to be acting this way. when i first crank the truck , i have great oil pressure, but the longer that i drive it, the lower the oil pressure goes.. it usually has good pressure for about 30 mins. or so... then, it slowly drops... when i'm driving it keeps a low pressure, but if i stop for a light , it will drop to nothing.. now, if i rev up the motor while stopped at a light the pressure will come back up to the low side... is it the oil pump, maybe??? all help- will be greatly appreciated....

 

[Southern3.0]

Might just be the gauge or the sending unit.

 

[tomw]

Might be that you have crumbling pan gasket material getting sucked into the oil pump pickup. That blocks oil flow, and will ruin your engine quickly. I have heard that you can use a coat hanger through the drain plug to scrape gasket crud from the bottom of the pickup, and then wash it out by pouring a fluid (Kerosene?) in the oil filler cap, and letting it push the crud out the drain. The pan is difficult to remove with the engine in the truck.
Do you have a real gauge with a dome-type sending unit on the side of the block? If you don't , then you are playing russian roulette with your engine. The small sending unit is actually a fake, just closing contacts if the pressure is over 5psi, running that through a resistor, and plunking the gauge into the middle of its travel.
Good luck, as they say...
tom