I have an issue with low oil pressure. The oil pressure gauge was working very erratically for a long time. I finally got around to replacing the oil pressure sensor. ...

I have an issue with low oil pressure. The oil pressure gauge was working very erratically for a long time. I finally got around to replacing the oil pressure sensor. Now the truth comes out. When the engine is cold it stays at about 40 psi. When the engine gets warm, the pressure drops. When I am running at speed it stays around 30 psi. At an idle it drops to about 5 psi and the "check gauges” lights come on. My guesses are either that I have a bad oil pump or worn bearings. It is not smoking or knocking. I am running 5W 30. I am going to switch to 10W-30. >>

Need help quick! Thanks in advance for the assistance.

I had the same problem in a Jeep CJ7 I use to have. After warmup, I'd have between 0 and 5 psi oil pressure. To bring things up a bit, I ran 10w40 synthetic and put in 2 to 3 bottles of STP. It worked and brought the pressure up to where I was comfortable. I know a lot of guys think the STP is snakeoil, but we used it for years in our stock car engine and never had one oil related problem. Give it a try.

Thanks,

I switched over today to 10W-30 and actualy had the same thought and put in 1 bottle of STP. I am going to see how that goes. I am a little hesitant about going to the 10W 40 right away. The owners manual is pretty adament about not using it. On the other hand, I change oil every 3000 miles so it really wouldn't have the opportunity to sludge up.

You didn't say how many miles were on your unit or the age but for now using 10w30 and some stp will help. Have you recently changed a camshaft on this engine and maybe nicked a bearing or changed a valve lifter? In the old days we just put in straight 30w oil in the warm weather and it helped an old engine through many more miles. The only problem with 10w40 is it is made from cheaper oil stock and not as durable as 10w30.