Thanks cruiser... I'll have to check that when I get resettled. I'm relocating to good ole southern Texas in a week or two here, so it will have to be after I get settled there.
My main concern and reason for the thread was to try to get to the bottom of the reason for the difference in psi between the OEM unit and my new replacement one.
It does sound like the new one is reading more accurately from the general consenus of those who have chimed in here.
Will check via your chart once I have time to do so.
Thanks!

 

Oh and if it makes any difference for mentioning the filter type.... I use the Wix XP for synthetic since I run the T6. What would that change if anything?

 

Soooooooo 50-60 PSI is high? Is that too high for the motor? My gauge shows that high doing 60MPH... I'm gonna hook up my OBD-II reader and get some more accurate numbers. My gauge may be reading high like ya'll are saying.
218,259 miles

 

By T6, do you mean Rotella T6 synthetic? If so, why do you use HD Diesel oil?

 

Maybe he uses it because our old school motors love the zinc and Rotella is some good oil at a good price also.

 

You probably have the OEM oil pressure sending unit in there like I did... I just replaced mine with a quality aftermarket one because it was leaking so bad. into the connector and everything.
That is what Cruiser and others are saying that know a lot about our jeeps... that the replacement sending unit is more accurate than my original OEM unit.

Yes...and I will only say this briefly because oil discussions can get a bit heated over differing opinions. I run it because of actual data sheets I've seen from places like blackstone and others that prove the actual content in oils (testing).
The T6 has a higher zinc content than other oils, and some research has shown that with our older style 4.0s with flat tappet lifter design, that it could reduce the wear for that style of motor. It's an old design, not like modern plants with VVTi and such. So many people here are fans of using the T6 in their older Jeeps too.
Along with the detergent package in the T6, really helps keep it clean too.

 

Sadly oil pressure is not monitored thru obd2. What i did was run a 3 way tee off the main oil hex .one side of the t goes into the hex. One side goes to the sender and the last side goes to an 18 inch grease gun hose where i plug in my mechanical gauge permanent . Will fire off a photo soon. When cold the jeep sender reads lower by a little more than 10 but dead on when hot

 

Like this?

 

I plan to install a Tee like that and put the sender on one leg but I am going to permanently mount a mechanical gauge on the other tee. Like others have said, Rotella T6 is a good oil for the 4.0 flat tappet I changed to it shortly after purchasing my XJ. I run the T6 5W40 which bumps up the oil pressure just a bit.

 

I just did that so I could check whenever I wanted with a mechanical gauge without removing the sensor.
Plus lets you compare the cluster and mechanical gauge at the same time so you know how accurate the cluster gauge is.
If I had any brains I should do what you are doing but have to figure out where to put the mechanical gauge where it won't bug me.
Plus since I have done that I have yet to take the cap off where the mechanical gauge hooks up.
Used thread sealant there and wonder how tough that is going to be to get off if and when the time comes.

 

I know from my industrial machine tool days that it is not good to leave a mechanical gauge connected permanently if the needle pulses because the gauge will not last long before it starts to leak. You need to install an orifice or choke in the supply line to smooth out the pulses. Good hydraulic gauges are usually fluid filled and have small holes for sensing.