First let me say I have done a fair amount of work on all kinds of cars, and while no longer in the business, I was once an FAA Licensed Air-frame and Power-plant aircraft mechanic.
Just completed an oil change on my 09 C300. Completed ah that is the issue...
I used a Mityvac extractor,( trying to avoid taking that pan off etc) a new one that I used a few weeks ago to do a Transmission fluid change on wife's Acura; it work perfectly, no issues.
In removing the oil on my Benz, I was only able to get out about 5.5 Qts?
I pulled and reinserted the tube Several times, I measured the insertion length against the dip stick, it was at least a half inch longer. I had briefly warmed up the engine before starting, I had pulled the oil filter first and loosened the oil fill cap also make sure there was no vacuum being created in the crankcase. I pushed the tube in as far as I could, pulled it back an inch or so, etc... ( then repeated all of the above) Nothing seemed to help in getting closer to the 8 Qts I was expecting.
I moved on and replaced the filter and proceeded to refilling the Benz, after putting in about 6 Qt is was Full on the dip stick. I started and ran the engine for a few minutes, waited about 15 while cleaning up and the dip stick showed full. What gives? The oil looked clean on the the dip stick and all seemed well just did not get out or need to replace 8 Qt, only about 6 at most.
Any idea would be appreciated. Next oil change (which I plan to do about every 7000 miles-10k just seems TOO long for me) I plan to do the drain method and compare...
please help...
thanks in advance.

I have the 4 cylinder turbo so I can't offer much other than to say it's always been spot on for extraction and refill.

Did you get any gurgling sounds?

Usually when I extract less on cars (when helping other people out) it's because it was low to begin with. But the math in your case says otherwise.

There was some noise, bubbling, gurgling and air sounds - maybe yet pulling in some oil and I saw bubbles etc in the tube - but no more oil flow like at the begin... I thought also that maybe it started out low .... that is why I just moved ahead and was careful not to add too much- just rechecked my left-over second 5 Qt Jug and at best used 2 qts from it... making a total of nearly 7 Qts to refill. Also seeing some posts with a controversy about the capacity as published by MB... some saying 7 Qts others 8.5 Qts. Guessing that may be some confusion on Liters VS Quarts??? I guess at worst case I changed most of the oil and a very dirty looking filter. I'll just be sure and keep a close eye on the oil level. I had checked it about 2 weeks ago and it showed very near full... but did not check it before starting the oil change.
Just hope to solve the mystery at this point - Thanks for the come back.

It sounds like it may have been a little low to start then. The extraction process is usually reliable.

Some people like to form the seal at the top of the dipstick tube and pull from the dipstick tube. But I don't think it would make much difference.

I was helping a friend and thought something went wrong when I only extracted less than a quart from his car. But it turned out it was just low. After some quizzing he told me he was getting an oil light, lol.

No experience with the oil extractor as I always drain my pan, but I would think if you were 3 qts low at the get-go...the oil light or a warning would have prompted on the cluster. Since you did not mention it, I would assume not all oil was retrieved.

I performed the oil extraction for the first time on my I4 a few weeks ago. I pumped out everything until I got mostly air bubbles and then shut the pump down for a few minutes. I restarted it and got a another 3-4 seconds of oil flow before I was back to gurgling and bubbles. If you're drain tube is hitting the bottom of the pan, you should be getting out just about everything.

No matter what method oil can keep flowing/dripping at small amounts from here until eternity.

A 4matic takes about a litre (a quart) less than the RWD version of the 204

Well the it seems the mystery will live on for now... Ive check the oil three times this week and it remains at the same level in the Dip Stick. I am not going to change it again just to see so it will be at least another 4 or 5 months before that happens. Thanks for the feed back all and Happy Driving.

Just changed the oil on my C230 4matic and it was very easy.

I removed around 7 litres of oil and put back in the same.


I used a $30 oil transfer pump bought off Amazon. Insert tube all the way down and away you go.


I drew about 5 litres quite easily then gurgling ect.


I pushed the tube down a bit further and let the pump go again for about 20 min. I let the car sit over night for the heck of it and pulled a bit more out the next morning.


The pump worked well and is cheap enough that if it dies I'll just buy another.

I had the same problem the first few times I did the extraction.

I have the oil extractor you get from Harbor Fright. I tried the insertion tube method that draws the oil from the bottom of the pan and I tried the seal-off method by sealing the top of the dipstick tube with a gasket/o-ring. Surprisingly, the second method worked better. I guess because it easier for the vacuum to draw from the top, once the suction has started, than it is to draw the oil all the way from the bottom of the pan. Either way, its SUPER slow but for me its still better than jacking up the car, jackstanding(which is a pain in the *** on this car), getting on your back and getting full of oil.

If you use the seal-off method(like the dealer uses), make sure its sealed really well or you will just draw air from around the seal and with all the gurgling going on anyway it can be hard to tell what is what. The Harbor Fright extractor I use has a bunch of insertion tubes for the bottom-up method if you choose that but for the seal-off method I just used the valve tip that comes on it with the double o-rings and replaced one of the o-rings with a little thicker ring. Its a really tight fit but thats kind of what you want.

Its a long process as you have to recharge the extractor several times to get all the oil out. If its gurgling and you think youre done, youre not. Recharge the extractor and do it again on a full charge. You need a good bit of vacuum to draw the oil. For the vacuum range on the extractor only about half the range is useful for drawing the oil near the end of the extraction process when the oil in the crankcase is getting low. Youre going to need a good air compressor, BTW.

For comparison sake(my results):

Bottom-up/insertion tube Method - 6.4 qts - 8qt refill
Seal-off Method - 7.2 qts - 7.3 qt refill

One more thing - when checking the oil level, this vehicles dipstick is really sensitive to the car being level in all directions. Put a level on the frame rail under the car and make sure its level front-to-back. Put a level across the shock towers to check level side-to-side.

One more tip - if youre using the seal-off method, replace and torque down the oil filter and leave the oil filler cap loose while its drawing the oil. Once it nearing the end of the draw(starts gurgling) quickly close the oil filler cap and leave it tightened until you recharge the extractor for the next round of suctioning. Assuming the crankcase is well sealed, this should prevent the oil that you sucked up into the dipstick tube from dropping back into the pan and causing you to waste precious vacuum getting the suction started again pulling all that oil from the pan back into the dipstick tube. Unless you have a badass extractor that gets all 8 qts in one draw.

W204 C350 V6
My extractor pype that goes down the diptick hole is 83cm long I have no problem.
I drive 10Km park car, wait hour and suck oil, byt that time most has drained off.
Had no problems so far.

Drive the car a few miles to warm up the oil, it's better than letting it idle. Oil is hotter this way, you'll easily extract more oil.