Oil Pressure Normal??

[PC300D]

Hello All, I am a newbie, and was wondering if the following is normal in reference to a 1984 300D T, 142K miles. When I first start the car the oil pressure is all the way up then after driving down my street, I stop at the stop sign, it's almost below the "1" driving at slow speeds(15-20MPH) it sits around "2" only when full acceleration or crusing speed is it at "3". Any Info Thanks, This site is great for new MB enthusists.

[t walgamuth]

will find that that is within normal range. check you r owners manual.

what kind and weight of oil are u using? also how many miles on this batch?

tom w

Although the pressure is probably within the normal range per the manual, it seems a bit low to me. Mine never gets below 1.5 bars at idle and goes to 3 bars between 1000 and 1500 rpm. I would make a note of the pressure before and after the next oil/filter change to see if it makes a difference. There is lots of info in this forum regarding the best oil and filter brands to use.

[polarweasel]

My oil pressure stays pegged at 3 bar any time I've got my foot on the accelerator. At idle, it's about 1.5-1.6, and the needle twitches a little. Is the twitchy needle at idle normal, or indicative of something catastrophic about to happen? The twitch is really only about a 0.01 movement, but it's still noticeable...

[pawoSD]

The twitching can be caused by an electrical signal minor issue, an oil pressure sensor thats a little worn out, or it could be the thermostat in the oil filter housing adjusting the flow to the oil cooler teeny bits back and forth, its all normal. Sometimes mine will fall to 1.3 bar after I've come to a stop, then it bounces up to 2bar then back to 1.3ish then back to 2 again....this is just the oil thermostat opening and closing and thus the flow/temperature changes. Its all very interesting....

[Ara T.]

My oil pressure will sit right below the 2 BAR mark when fully warmed up... i have seen others' cars and usually their's is around 1.5 warmed up, what does this implicate?

[rg2098]

Originally Posted by pawoSD

The twitching can be caused by an electrical signal minor issue, an oil pressure sensor thats a little worn out, ...

His car uses a mechanical pressure gauge, not an electric like the W126.

[tjohn]

Originally Posted by PC300D

When I first start the car the oil pressure is all the way up then after driving down my street, I stop at the stop sign, it's almost below the "1" driving at slow speeds(15-20MPH) it sits around "2" only when full acceleration or crusing speed is it at "3". Any Info Thanks, This site is great for new MB enthusists.

I think that's normal. Or, more accurately, if you're saying what I think your saying, its normal. Per the manual you should have at least .3 bar at idle, most people have 1.5 or so. You should peg the dial on acceleration, and it sounds like you do. The concern I have is the last thing you wrote. When you say crusing speed, I assume you mean anything over 30 mph or so. You should not have to drive 60 mph to peg your gauge.

Type of oil can make a difference. With Chevron Delo (a dino oil) my gauge behaves similar to yours. With Mobil 1 15w-50 (a synthetic oil) my dial never dropped below 2.

[PC300D]

Thanks everyone, I also wonder about the oil and filter, I was going to try some mobil 1 but heard conflicting reports about seals leaking after mobil 1 use, could just be one guy's experience or a rumor. Thanks again for the info.

[t walgamuth]

shared what oil you are using, but generally heavier oil will result in higher oil pressures. on a worn engine, which yours may be, i always err on the side of using the heaviest oil that the manual allows for my temp conditions.

tom w

[scagle]

i just got the 240d 82 running that was abandoned for 3 yrs. when starting up the oils at 3 and pretty much stays there. 2.5-3 generally, is this bad? changed oil put in 40weight

[t walgamuth]

really good. no worries.

is the 40 w diesel rated?

tom w

[Dervman]

Originally Posted by PC300D

Thanks everyone, I also wonder about the oil and filter, I was going to try some mobil 1 but heard conflicting reports about seals leaking after mobil 1 use, could just be one guy's experience or a rumor. Thanks again for the info.

Be sure to use either Mobil-1 15W-50 or the Mobil-1 Truck & SUV 5W-40 (aka Devlac). These are the only Mobil-1 synthetic oils that are Diesel Engine rated. This is important for their soot suspension additives amongst other things.

Synthetic Oil's have a fairly strong Cleaning action that will remove any accumulated deposits in your engine including those around seals. If the crud around the seal is all thats stopping it leaking, then yes, you will get some seepage. The good news is that synthetics also have special additives to soften older seals so given time - unless the seal is beyond recovery - there is a good chance that the leak will stop. Most people panic at the first sign of leakage and switch back to dino oil without giving the seal a chance to recover.

Because of the cleaning action you may want to replace your oil filter after a couple of thousand miles to avoid any chance of it being plugged by the crud

[willrev]

I just changed my oil and used the diesel rated Castrol Tection and two quarts of the Lucas Oil Stabilizer.

The Lucas stopped my blowby and oil consumption. It is a great product. Lucas makes some good stuff. It is compatible with Mobile 1 or the Castrol Tection or Rotella, really any oil. There is a different Lucas stabilizer for synthetics.

[scagle]

don't make a habit of using that stuff. I've heard that if you use it all the time, if you take apart the valves there will be a gooey thick layer stuck to them. this will decrease your power and your milaege