1994 SL320 with 96,000 miles. I bought it just 4,000 miles ago. When it starts, the oil pressure reads 3. Stays there for 15 minutes or so. When you put it in gear, it may read 1 to 1 1/2 on the gauge. If you drive it another 15 minutes, and come to a stop with it still in gear, it may read ZERO at the gauge. I see there is a warning light if it goes below 1, but the light never comes on.
I just put new oil and filter, and does the exact same thing after the oil seems to warm up.
Where should I go from here?
Thanks for any help.

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Schettini
1996 S420 (45,00O)
1994 SL320 (96,000)
1992 SL500 (82,000)
1990 300E (183,000)
1993 300E (99,000) sold
1988 190D (125,000) sold

A warning light if it goes below 1? Where did this information come from? I would think it would rather routinely fall below 1 at idle. What does you owner's manual say about it? In any case you're getting eratic readings and the place to start is likely the sending unit at the base of the oil filter - fairly inexpensive and easy to replace.

Hope it is not 5W synthetic.

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1970 280S M130 engine- good runner
1971 250 M130 engine- #2 rod bearing, gone
1971 280SE (blown engine,parts car)
1977 German 280S W116-only 33 years old

The warning light should be for low oil level, which has nothing to do with pressure.

You need to hook up a manual guage to confirm what the electronic one is reading. For my turbo charged engine MB wants .3 at idle and the full 3 bar by 3k rpm's. I imagin the M104 can't be all that different. Most seem to idle somewhere between 1-2 at hot idle. It should of course peg as soon as you bring the RPM's up.

I'm not very familer with the M104 and you may not even know what to look or listen for. But if it really has no oil pressure I would think the lifters would protest, you should hear a pretty good racket when you lose pressure. If you are unfamiler with what to look for I would have the car flat bedded to a good shop and let them hook up a mechanical guage to see what it really has. Driving it with no oil pressure will ruin the motor, and I bet a rebuild is $8k.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

As I recall, the oil pressure gauge on the early 129s is like the one in my 140 - it includes a light, which should come on when the pressure falls below a safe level. The handbook says nothing of a minumum pressure which should be shown on the gauge.

The oil pressure gauge in my 126 on the other hand does not have the light and, indeed, the handbook indicates that 0,3 bar is still safe at idle.

The oil level light has, as you wrote, nothing to do with pressure.

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Mateusz
1986 126 500SEL
1986 126 300SE
1992 140 500SE
1996 124 E200T
1999 210 E320T
2017 205 C200T mit Schaltgetriebe!
2010 639 CDI 3.0

That's what I have in my car...is there a problem?

...I hope you aren't just going to go on about how thicker oil is better...

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

I recently bought a 1995 E320 with 169K and the oil pressure was reading almost exactly like yours. I replaced the sender unit and now the pressure very seldom goes below 2 at idle when hot.

Thanks for all the responces.
Just a few things,
The light I'm refferring to is on the oil pressure gauge, it looks as if there is a place for a light between the numbers 0-1,(just as the one for low fuel level). I believe there is a seperate light for oil level. The oil just put in was 10-30 Vlvln High Milage.
As far as noises, THERE ARE NONE! It runs and sounds perfect. At startup the presser is at 3, even with the engine HOT, and you step on the throttle, again it pegs at 3.
The main issue I have is that it drops to Zero at idle (with it in gear).
What's the cost of a sending unit? (a previous post said it's below the oil filter? not a big job?
Many Thanks.

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Schettini
1996 S420 (45,00O)
1994 SL320 (96,000)
1992 SL500 (82,000)
1990 300E (183,000)
1993 300E (99,000) sold
1988 190D (125,000) sold

If it were my 1994 SL320 I'd be using 15W40 mineral oil or Mobil 1 15W50 synthetic oil. It's a good idea to replace the sending unit so the oil pressure gauge is reading accurately. If the oil pressure is, in fact, 0 you'll have major engine damage very soon

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Fred Hoelzle

That light on the pressure guauge should illuminate with the switch in the on position just before starting as that position checks all the lights on the gauge cluster.

Click on "buy parts" above to check the price of an oil pressure sender for your car. The location of the warning light wouldn't be an indication that it necessarily comes on at 1.0. Pressure below 1.0 is quite common.

I just turned the key to the on position, and the light on the pressure guage does in-fact light up red. I have NEVER seen this light come on when the pressure is below 1.
Now Is it the Oil pressure sender unit or could it be something else?

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Schettini
1996 S420 (45,00O)
1994 SL320 (96,000)
1992 SL500 (82,000)
1990 300E (183,000)
1993 300E (99,000) sold
1988 190D (125,000) sold

What does your owner's manual say about when the light should be lit?

Your idle pressure should be reading around 1.5 - 2.5 bar depending on the viscocity of the oil you currently use.

I've replaced the sending unit on my M104 (300E) twice. The unit costs around $65-$70 and can be replaced in less than 30 minutes.

Access to the unit is under the vehicle. A bit tight to get to as you have to maneuver around the starter and the harness. I don't remember what wrench size to use, but make sure it's a short one...not a lot of room to turn, but after a couple turns, you can hand loosen and remove.

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

It took me a while to get to it, but I just replaced the oil pressure sender, and it is working great. Pressure has not dropped below 2 bars.

Thanks for all the input!!!

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Schettini
1996 S420 (45,00O)
1994 SL320 (96,000)
1992 SL500 (82,000)
1990 300E (183,000)
1993 300E (99,000) sold
1988 190D (125,000) sold