Is the oil stick you purchased from ebay the special one as indicated below?
From rxjr22:
@rxjr22
Save Time and your Sanity. Buy a engine Oil Dipstick motor tool level for mercedes benz (MB Tool
#120 589 07 21 00) also known as a MB technician oil dipstick.
In case you haven't seen one of these or read how they work, it is called a 'workshop dipstick', and is very different form normal conventional dipsticks. Several Mercedes models from 2001-2009 did not come with engine or transmission dipsticks from the factory. This tool is what they supply for purchase and is used in all of those models, so it is universal and can NOT REMAIN in the vehicle. It has measured markings all along the stick very similar to a ruler, and you insert the dipstick down in the tube (it can be very tight, due to multiple bends in the dipstick tube) until it stops/bottoms at the oil pan, and there is typically 4-8 inches still sticking out the top of the tube. You then remove the dipstick and compare the reading to a chart that we provide that shows what is the high/low readings for every model this dipstick applies to. It's honestly not the easiest or simplest way to check the oil in your engine, but unfortunately, this is what Mercedes has designed for us and is the only way to check the oil level other than using the factory computer which costs thousands of dollars. This also allows you to see the quality or cleanliness of your cars oil. Works like a regular oil dipstick. Be sure to remove from your car after measurements are done.
From Phil1987uk:
161 mm = minus 0,5l
167-169 mm = oil level correct
175 mm = plus 0,5l
So basically it's not like a normal dipstick made for the car, it can be used on many. I need the correct measurements, on that thread it says 142mm? On this one it says 167mm-169mm.
This attached pdf should help