I have a 1997 GMC Sonoma 4.3 5 speed. Truck was running fine oil pressure and all but my oil was turning to chocolate milk and we all know what that means. So I changed the head gaskets and intake gaskets and all the ones in between. I cleaned the lifters and valves and everything else I could touch. I cleaned the screen on the oil pickup tube as well. It was almost stopped up. Anyway when I got it back together it ran great with no more chocolate milk,but, as soon as the engine gets to operating temperature the oil pressure drops to almost nothing at idle. As long as rpms are up past 850 it's ok but at idle and operating temperature the oil pressure drops to almost nothing! I know the oil is good. I put a new oil pressure switch on. I put a new high flow oil pump in. And most recently I changed the rod bearings! Still dropping oil pressure. I even put the Lucas high mileage thick stuff in but still dropping oil pressure and I have no clue what to do next! Can someone help?

 

850 isn't that high off idle, what viscosity oil are you using?

 

i am using 10w/40 with a quart of the oil stabilizer stuff that is pretty much just like lucas. its even in a very similar bottle. anyways its pretty thick and suppose to up ur oil viscosity and raise ur oil pressure but it didnt work either