2006 Buick Rainier stalled. The oil gauge reads

Check your oil level

80 is ok unless it says 80 when the engine isnt running,turn on ignition and check the oil pressure,it should read 0....

Could be the gauge on the dash. If you really had no oil pressure the engine would be very loud.
A mechanic would check oil pressure with a mechanical gauge to verify.

that is a sign of the wrong oil grade. that truck takes 5 w 20 oil

Copy and paste,here's your problem,the sensor is screwed into engine by oil filter,http://www.autozone.com/autozone/parts/2004-Buick-Rainier-2WD/Oil-Pressure-Switch/_/N-jldd5Z8znc6?filterByKeyWord=oil+pressure+switch&fromString=search

The oil pressure should be verified by removing the oil pressure sending unit and installing a gauge to take a direct reading. If the oil pressure is ok, the problem is most likely a bad pressure sensor (although it could also be a bad gauge or circuits).

If the gauge verifies that the oil pressure is indeed low, then the oil pan needs to come of for an inspection of the oil pick-up tube and the engine bearings.

It could be the sending unit. If the truck is low on oil it will cause something similar. Be sure the oil level is topped up. The only way to be sure it so measure the actual oil pressure at the engine with a proper gauge..

THESE ARE POSSIBLE CAUSES TO YOUR PROBLEM. CLASS 2 CIRCUIT IS OPEN SHORTED TO GROUND OR TO B+. THE PCM IGNITION POWER CIRCUITS HAS A HIGH RESISTANCE CONDITION. THE PCM MAIN GROUND CIRCUITS HAS A HIGH RESISTANCE CONDITION. THE SDM MODULE COULD BE SHORTED PULLING THE VOLTAGE LOW. THIS MORE LIKELY DEALERSHIP FIX.

Check oil level.
First verify the pressure is dropping and not some other problem.
You will need to connect a pressure gauge to the engine to read the true pressure.
If the pressure reads good then the sending unit is bad.
You should have new oil and filter. A bad filter can cause pressure drop.

MY 2002 RAINIER DOES THE SAME THING I HAVE BEEN TOLD IT IS THE THROTTLE BODY. I NEED TO CLEAN IT OR REPLACE IT. I HAVE THE 4.2 AND YOU CAN GET ONE FOR $200 PLUS SHIPPING. THE THROTTLE BODY STARVES THE CAR FOR AIR CAUSING THE IDLE, AND SHUT DOWN PROBLEMS. I AM GOING TO TRY IT THIS WEEKEND.