[Jerry Bransford]

Most likely just a bad oil pressure sender, replace it with a Mopar replacement. Aftermarket oil pressure senders have a bad reputation, especially store brands. This is a very common problem with TJs.

 

[Jerry Bransford]

Acceptable oil pressure is 10 psi per thousand engine rpms. The oil pump is engine driven so the real oil pressure rises and falls in step with the engine rpms. Early TJ oil pressure gauges show the true oil pressure complete with its ups and downs. Later TJs around 2003 had their oil pressure gauges reprogrammed to stay mid-scale no matter what the real oil pressure is. The factory changed it because most new TJ buyers had never had a real oil pressure gauge before and too many refused to believe the oil pressure was supposed to vary up and down. Dealers were getting buried in complaints about the oil pressure dropping at low or idle engine rpms, they asked the factory to reprogram it for that reason.

 

[Jerry Bransford]

All TJ gauges are 100% computer driven.

 

[Jerry Bransford]

So Jerry, given that mine is an 00, is my drop in oil press real? Never dropped below 20 on the mark till month or so ago. Cause(s)?

Yes your oil pressure variations are, as described above, 'real' and normal. Just keep in mind the rule-of-thumb of 10 psi of oil pressure per thousand engine rpms being acceptable to know if it's ok or not. And perhaps you just never noticed it dropping at idle rpms.

 

[Jerry Bransford]

Yep, it's a total dummy gauge. The "sensor" is nothing but a switch that closes at approx. 3 PSI. The computer moves the needle around a bit to fool you into thinking it's a real gauge.

X2 exactly.

 

[Jerry Bransford]

The factory temperature gauge is more than up to accurately letting you know what the engine's temp is.

 

[Jerry Bransford]

I hope so, however, as Mr. Bills noted most don't seem vary with engine load (112 deg. in my case; figured it is just the display/sensor) so I am a bit concerned that it may not display over temperatures correctly...
Since I will need to fill up both gage positions in the A pillar gauge pod (tried hard, unsuccessfully, to find a singe gauge pod) I figure that I should go for the most useful gauges.
If you had the choice which would you choose a transmission fluid (after the cooler) temperature gauge or an engine temperature gauge... or something else?

Enjoy!

Transmission ATF temperature gauge and a cool analog clock like an old aircraft clock. You don't need a second engine temperature gauge. The engine temp gauge doesn't move around much because the OE cooling system has sufficient excess cooling capacity so the temp gauge doesn't move much. Mine does move up/down a tad at times if I'm towing my tent trailer up a steep long mountain grade on an extra hot day so I know the temperature indicator is not sitting in a fixed position.