Oil level help

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Active Member
Feb 12, 2017
C220 w204
2007 w204 220

When engine cold where should the oil level be on dipstick..

I have always been taught at max fill level


A local independent Merc specialist said just over half... seems low to me

He said it allows for the oil pressure to rise when warm and at higher motorway speeds..!!

Any help plz
He's right. Oil expands as it gets hot so the level rises on the dipstick. IRRC the difference between fill and full marks is around 2 litres on the OM651 engine. When changing the oil there is usually around a litre left in the various oilways meaning if the oil is refilled using the official capacity- its slightly overfilled. An overfilled sump may allow the crankshaft to hit the oil in the sump causing aeration of the oil potentially starving the engine of oil- it may also increase sump pressure forcing oil vapour into areas it shouldn't clogging them up and contaminating exhaust emission cleanup devices. - not a good idea! I like to see at least a 5mm gap between the top of the oil and the full level on the dipstick when the oil is HOT so I guess this would translate to
1/2 to 2/3 full when COLD.
Yes, you're supposed to run the engine to temperature, then park up on flat ground, stop engine, wait 5 minutes, then check.

Checking when cold is pointless because everything expands when heated, so you want to check when it's hot, to know it's not overfilled.
2007 w204 220

When engine cold where should the oil level be on dipstick..

I have always been taught at max fill level

Make up your own mind on this, I do the opposite of the advice given already.
On my CLK, I always check after it has been sitting overnight and make sure it is filled to the full level when cold.
It's now almost 12 years old, 135,000 miles, doesn't burn oil or suffer from any engine or oil related problems. Only thing I insist on is using Mobil 1 & changing it midway between each service too.

Although I too was a fill to Max devote there is no magic or real benefit from doing that. MB are happy for you to run anywhere been min and max and the engine will be safe. There are only two variables to bear in mind other wise run it where ever you want:

When running at max it will take a little longer for the oil to reach optimum operating temperature which is not good if the car is routinely short tripped.

If the oil is being run on long drain intervals, say 12-15000 miles then running at min risks using up the oil additives.

I would never fill to max with the oil cold. If the oil is going to be checked cold I'd fill to no more than 3/4.

What I do is personally is run at 1/4 above min and change the oil annually at 5000 miles. To fill to max in those circumstances would simply be to waste oil.
To check the level the engine needs to be cold .If checked hot, lots of oil will still be in the oilways of the engine and valve covers .Waiting for it go cold , by then , the oil will have made its way back down to the sump. The idea of half way on the dipstick is a good way to go. A maximum mark on the dipstick means just that, you can keep it on the max mark if you want to . You get a service from M/B it will come home on the full mark ,or maximum .Ans some times over filled , so check it on return from the service.
Preparing for a long trip I checked the oil level and topped it up to the full mark. On then driving away, not far, the display told me that it was over full and should be drained or risk damage to the engine. Took it to the MB dealer who very kindly, and for free, did it without delay. I asked them about the display and was told that the sensors are too sensitive and generally they fill them no more that 3/4. Some time later collecting it after a service I got about 10 miles and the display was telling me too little oil add 1 litre. Took it back and got profuse apologies and they topped it up. I always get charged for 9 litres which is the stated maximum capacity. Must remember to check the oil immediately after a service just to see how much actually gets put in.
the sensors are too sensitive

They also aren't accurate & shouldn't be taken as gospel.
I've experimented with mine, every time I've drained the oil the sensor never reads below 1.4 litres when empty. When filling up to the 6.8 litres my CLK holds, no matter how much oil you pour in, it never reads above 6.4 litres.

I no longer pay any attention to it & rely on a dipstick which is always 100% accurate.


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