Lower oil pressure
 

My oil pressure at idle has always been around 2.25 to 2.5 and will always peg out at 3 under load. Today, after approximately an hour drive on the freeway, for the first time I noticed that the pressure has gone down to just a hair below the 2 mark at idle. Anything I need to check or be concerned with? :confused: I’ve had the car for just over 2 years now and this is the first time I’ve seen the pressure this low.
I’m currently using Delvac 1 oil if it matters any…
Thanks.

No, thats great oil pressure. MB says at idle the pressure can drop to .3 bar.

In my cars the oil pressure will usually work its way down around 2-2.5bar at idle as it approaches oil-change time.

Nothing wrong with it at all.

I'm pretty sure the manual for my 124 says 0.7 bar minimum, although I can't check because my car is at the other end of the country unfortunately. When hot, mine drops to around 1.5 at idle. I've had it go down to just over 1 at idle after climbing a long mountain pass in the summer. Engine temp was 100+ at the top of that hill, good thing I had Mobil 1 in there ;)

Normally pegs at at about 1300RPM when hot.

Not sure as to why it would change, but I have also experienced odd days where the pressure will be around .9 bar or so. Usually it is at 1.3-1.5. It's only happened to me two or three times, but I have noticed that on these days, it is excessively humid out.

A possible difference due to Atmospheric pressure?

All our diesels idle around 2 bar when its cold out, and about 1.5 when its hot out.

The 300E idles at about 1 - 1.5 bar depending on temp.

Even on the hottest days during the summer, my pressure never dropped below 2.25 at idle. This time around the ambient temperature was around 60* ?
Thanks to your responses I’m not really worried anymore :), but I’m just wondering what might have caused the sudden change…

It could also be age/wear and tear on the oil pressure sensor itself....they eventually wear out and the result is that they read low. Mine got so worn out that it was reading close to or at 0 at idle.

Are you using Delvac 15W40? I always add Lucas engine oil stabiliser to mine. I idle hot at 2.25 and run at 3 bar.

pawoSD – hhhmm… that makes sense. Other than the lower oil pressure, the engine is running very smooth without any unusual noises.

MBNRA – I’m running Delvac 1 (5W40). I’m not sure about running any oil additives like Lucas in my car.
http://www.bobistheoilguy.com/images/lucas/lucas.htm

I'm not so sure about those results in Bob the oil guy's testing. For one, Oil stabiliser used in an engine doesn't foam because it is under oil pressure and any oil will foam when you blend it around fast enough! I've never seen signs of oil foam in my car and I lift the hood when never I stop after a long didstance drive. The one thing I CAN tell you is that Lucas "Keep that engine alive" causes the engine oil to cling to my timing chain and it keeps it well lubed. you can see it through the oil filler cap.

Second, oil stabiliser is not meant for gear lube! These two lubricants are totally different and in a rear end or other gearbox what you want to use is Lucas hyperlube for these. I have used Lucas oil stabliliser in my engine for the last 209,848 miles and have less than 2* of chain stretch and oil sent out for analysis shows no appreciable metal content! Compressiion is still at 330 PSI per cylinder or better. I'm not going to convince everyone that an oil stabliliser is going to be good for them, but I trust real world results over a motor driven gearbox in front of a camera anytime!:D

You said you noticed this after a 1 hour highway run. Is this the first time you have taken a long trip is a while?