I did some research on oil extractors. The ones that I found to have some merit are the one sold by Griots and the Pela PL-650. Both these units (they may be the same) hold 6.5 liters, are transparent, and come with two different size insert tubes. The web sites are:
www.griotsgarage.com
http://shopus.diy-boat.com
www.overtons.com
For Griots search on "oil". For the other two search on "Pela".
I am still hesitant to order one for my C230 Kompressor for the following reasons.
1. The dipstick tube on the M271 engine has three sharp bends in it. I am not sure I will not kink the plastic tube.
2. There have been some complaints on other web sites that sticking the plastic tube into a hot engine causes it to become very compliant or in the extreme case melt.