So I took my '95 Aurora out for a little excursion today and while she ran flawlessly most of the way, I got a 'Low Oil Pressure' warning on the DIC right after I got off the highway a few miles from home. Pressure would dip to 6 or 7 psi when I was stopped at a traffic light and then recover to the low 20s once I got under way again. The temperature gauge was also reading quite a bit hotter than normal. It usually sits a hair above 200 degrees but by the time I got home, it was closer to 240. Not boiling over, but a good bit hotter than I'm comfortable with.

After the engine had cooled down for a couple of hours, I checked the oil and the dipstick showed just a hair above the 'add' mark. When I cranked the engine and ran it at idle for a minute, the oil pressure sat at about 23-24 psi. I put in a little more than a quart of oil and ran the engine at idle again and pressure doubled to about 46-47 psi. I figure the elevated temperature was mostly a symptom of the low oil level.

I don't drive this car very much at all anymore since I got the Impala, but I will continue to monitor the oil pressure and level. Anything else I should pay attention to? Also, does the Aurora 4.0 have the same tendency toward upper pan seal leaks that the 4.6L Cadillac variant of then engine does? For reference, what should the pressure in a first generation Aurora 4.0 V8 normally run?

So I took the Aurora out for a little run to go get some dinner earlier this evening. I don't think I went ten miles. I checked the oil before I set out and the level was right at the 'max' line on the dipstick. The oil pressure was in the upper 50s as I started out and by the time I got to my destination it was in the low 40s. On the way back, it kept going steadily lower and lower, staying in the 20s and low 30s most of the way, dropping into the teens when I'd stop at intersections. I'll check the oil level in the morning and decide on further action then. I'd still like to know what the normal operating range is for oil pressure.

You are probably getting erroneous readings from the Oil Pressure sensor/sending unit.
Even though I would recommend a Delco for replacement, my Standard oil pressure sensor is still reading correctly 1.5 years later now.
Oil pressure can vary, mine reads 70psi cold start up and drops to 50psi above idle, and 33 psi hot/idle.

That thought had crossed my mind as well. I had a similar problem with that component on my '91 Cutlass Supreme many years ago. I'll definitely have that looked at.

I just got off the phone with my mechanic and he did not have good news. He'* replaced the thermostat, which has indeed helped the temperature, but the low oil pressure problem remains despite his putting in a new oil pressure sensor and replacing the oil with 10W40. It'll now run a little longer before the pressure drops off, but the problem isn't solved. His recommendation was to consider getting rid of the car before the head gaskets go. Needless to say, I'm kind of bummed.

A string of thunder storms yesterday pushed the temperatures here down into the 70s for the first time in several weeks, so I decided to take the Aurora out for a little drive for the first time since I parked it in disgust a couple of weeks ago. Oil pressure stayed between 16 and 25 psi. during the entire 45-minute drive but would drop to about 8 psi. at stop lights, just a hair above the point that the 'Low Oil Pressure' warning would trigger. The temperature stayed steady at just a tick over 200 degrees. I finally pulled the car back into the driveway and put it in 'Park' for a minute and within about 45 seconds, the temperature climbed just above the first thin mark past 200 (220?) and the 'LOP' warning sounded. The takeaway from that little experiment was that ambient temperature is a factor and I can't drive the car on 90+ degree days. I'd still love to identify and fix (if feasible) the root cause of the problem, although if I found the right toy to replace it I wouldn't hesitate to sell that car and let it become somebody else'* problem. Meanwhile, I'm just thankful for the Impala, boring as it might be.

Like Soft Ride said, you need to take a look at the oil pressure reader and sending unit. How are the RPMs at idle since you mentioned that you're getting 6-7psi? Maybe just replacing the sensor would solve this issue.

90 degree days are not easy on any car, if the whole system is not up to speed.
The thermostat,cooling fans must be working properly, rad passing a pressurization test and consider a coolant flush if it has not been done in a while. I do my coolant every 3-4 years with Prestone long life.
Still when it is hot outside I see 220F when tuck in traffic, and in the mountains on my last trip, I hit 235 after a 10 minute long steep hill climb.
I pulled over for a break, let the car cool down for 25 minutes with the hood open. (lets the wheel bearings cool too)
Instead of a 195 degree thermostat in summer, a 185F opening temp rating would be beneficial.
Did the mechanic hook up a mechanical gauge to read the actual oil pressure?
If not, this is the only way to confirm what the true/ real pressure reading are.

Yes, the cooling fans are working properly. The radiator was replaced in January and it got new coolant then and again when it went in the shop with this oil pressure problem a few weeks ago. At that time, the thermostat and oil sensing unit were changed and the mechanic even replaced the oil with 10W40. The new thermostat does seem to be doing a somewhat better job of controlling the temperature than the old one did. I don't know for sure whether the mechanic hooked up a mechanical gauge, but he'* very thorough about investigating problems like this. He did say he was going to test the oil pressure with his meter to rule out a faulty reading. I doubt he would have been talking about an OBDII scanner since this car is a '95 model.

How many miles on Aurora engine?
Has the water pump been replaced?
Has the engine received a compression test?
If you can, confirm with mechanic that he used a mechanical gauge to read the Oil psi.