I found on my 500SEL that the oil does expand quite a bit. If I check it after a long hard run (say a tank of gas at 65 to 70 mph) and check it after about 10 min, it will show above full. Let it cool down over night and it will read maybe a quart less. My dip stick is 2 quarts between add and full. The other thing I found was that you need to insert the stick and wait 10 to 15 seconds before removing it to see the level. The reason for this is the dipstick tube goes all the way down to the oil pan. On the dipstick there is an o-ring to seal the dipstick when installed. These two things together make a kind of plunger that pushes the oil out of the tube. You must let it set for the few seconds to let the oil come back up into the tube. Try it sometime. Insert the dipstick and immediately pull it out. Check the level. Now insert it and let it stay in for 10 sec, remove it and check the level. You will find a big difference. I have never tried it on the 300D but I am sure the same thing will happen.
Paul

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84 500 SEL (307,xxx miles)