Ok so here's my deal, I've got a '00 xj with the 4.0L on 33's and a 6.5 inch 3 link lift. Every so often the oil pressure drops low enough the check gauges light comes on. It was an issue before my lift n tires in early august. It only happened after driving on the highway n then stopping in traffic, till today. Today the needle dropped to zero and it was only running and moving for not even a half hour. I've also been noticing an occasional squeak/squeal sound but doesn't seem to have any effect regaurdless of what the oil pressure is at. When running after warm up and at a stop the oil pressure needle is on or just above the first line above 0. While driving its anywhere from the second line to just over the 40 mark. I really don't wanna wait and see if the motor seizes from lack of oil due to a bad oil pump. Or maybe its the oil pressure sending unit playing tricks on me. Any help would be much appreciated.

 

What kind of oil and filter are you running? One time I changed my oil with some garbage oil and oil filter ( poor college kid ) and my oil pressure was much lower around idle about 5psi. then would only get up to 40psi on the highway. I changed it after about 1000 miles back to good ‘old pens oil and a fram filter and its always about 35psi idle and 40psi running. 1997 4.0 xj.

 

Oil pressure switch. Commonly gets smacked during an oil change. Get a new one and see if your issue changes. 40+ psi while cruising is awesome pressure, which leads me to think you have a sending unit (switch) issue. Any coolant loss?

 

I would verify the oil pressure with a static gauge. (13 psi @ idle when at operating temp) If o.k. then replace the switch

 

I'm running Mobil 1 10w40. N team tough guard. 13 psi warmed up n movin sounds rite n highway is more like 40. I'll try that oil pressure test tho