Oil pressure guage

[XLT03]

My 92 Explorer 4.0L oil pressure gauge needle is fluctuating alot suddenly. I replaced the oil sensor and the problem seemed to go away and the needle now sits in the middle to the gauge. A few days later the needle started to drop. I notice this especially at low idle such as when parking the car. The guage would show normal pressure and then drop to low pressure and back to normal. Any ideas?

[Opera House]

It is time to attach a real gauge to it. The sender you have turns on at about 6#. Since you replaced the sender and still have the problem, your low pressure problem sounds real. Unless you are running really thin oil, you have big problems, clogged inlet screen, relief valve stuck open, really bad bearings. Unfortunantly it is very difficult to drop the pan, the engine must be lifted. Normal pressure is 50-60# at startup, 40# highway hot, 17# hot idle.

[XLT03]

OperaHouse:

Thanks for info. Vehicle has 147,000 and uses 5-30 and is changed every 3500mi. I did change oil & filter yesterday and haven't seen any fluctuation since. Will keep eye on this and if I see fluctuation again I'll attach real gauge.