Should be between 20 and 40 psi at idle
Around 40 psi when at at operating temp.
At operating temp. and at idle, it should be no less than 11 psi
A full operating temperature it will be around 40 psi.
You can get gauges with instructions at auto parts stores Oil Pressure, engine temp, amps or volts
It will depend on the temp of the oil. When it's cold, the pressure will seem high - but it will drop once the oil comes up to the operating temp of something like 210-225 degrees F. When driving at temp, the pressure on my 06 seems to stay around 30 or so; there is a line on that screen in the middle of the scale that it typically stays around when driving. At idle, at temp, the pressure drops off to very little.
6 psi when it is at normal operating temp. seems wierd but its spec.
The oil is hot and the rpm's are low. When you first start up the internal rotating parts are colder and tighter then at operating temp which will drive the oil pressure up, as the engine gets to operating temp the gaps around the internal rotating parts change due to temperature, causing oil pressure to drop at an idle. Most people never notice this due to having warning lights instead of gauges.
The plug or sensor above the oil filter on a 1996 Cherokee is the oil pressure sending unit. This sensor controls the oil pressure gauge.
The oil pressure sensing unit is right above the oil filter on the front of the 4.7L 2001 Grand Cherokee.
Around 30-40 psi when at full operating temperature. Can even be somewhat lower on a high mileage engine.
This is normal as when the engine warms the viscosity of oil lessens, thus also reducing the oil pressure. On a cold start the oil pressure is on the high side, say reads at 75 at idle, then at operating temperature it can just read between 25 to 50 at idle speed, depending on which viscosity rating of the oil you use.
The pressure will be high until the oil reaches full operating temperature.