So I bought a 1994 E320 recently. When I first got it, the oil pressure sat around 2 at idle, but whenever i got on the gas, it went to 3. i did some work to it, and I drove it up my driveway with no serpentine belt (The car was running for 60 seconds like this) and now the oil pressure is at 3 regardless of what I am doing.

What did I do...

 

If it rises when your drive that's fine.

If it now is at 3 even when only idling, then that's fine as well.

The main thing is to have good oil pressure when driving. At idle it is acceptable, though not ideal, to have the pressure be at 1.

 

Thanks for the response. I let the car sit for about a week or so while I ordered some parts. I noticed for the first 10 minutes of driving it for the first time in 7 days, the temp gauge and oil pressure gauge did not work. Oil pressure was always at 3, and temp was always cold. Is that normal when the battery is unplugged for a while? It was really weird. But 10 minutes in, the oil pressure dropped to 1.5-1.7 at idle and the temp went 80-100. This is the weirdest car I have ever had.

 

Don't confuse excellent engineering for weird.

What you have yet to realise is that you are dealing with a car that has real instruments. Most cars have instruments that simply stay in their "normal" zone and don't waver unless there is a problem. The W124 is a vehicle that has a temperature gauge that will go up and down, as the coolant temperature goes. So, as long as the coolant temperature is cold, such as first thing in the morning, after sitting for ten days, the temperature gauge will simply reflect the actual coolant temperatures.
Just about every other car on the market has a gauge that will resolutely "sit" in the middle of the gauge, where "normal" is and not move as long as the coolant temperatures are within the normal range for coolant temperatures.

Same thing with the oil pressure. While cold, the viscosity will be higher and peg the gauge at idle. As the engine heats up, the oil "thins" and it doesn't peg the oil pressure gauge. Most cars with an oil pressure gauge have one that just sits in the "ok" range of the spectrum.


Realise that you can tell the health of your engine by simply taking notice of what your instruments are doing. It's ok for your coolant temperatures to go beyond 100 occasionally. Once they start staying there consistently, then you have a problem. Obviously ambient temperatures play a significant part in making an assessment.
Same thing with the oil pressure gauge. If it fails to rise to 3 when driving then you've started to have oil delivery problems. Could be as simple as having your oil pressure sender changed, or could be worse.

These cars are (mostly) very intelligently and logically built When I look at some of the details, I marvel at the simplicity (sometimes) and logic of what they were doing. Others things just confound me (air con condensor!!!)