Welcome to the forum!
Definitely check the oil regularly.
When the car is running, go someplace, park the car someplace clean and see if there is any drip.
You may have another leak somewhere.
If you can, try to stay away from Strauss and Jiffy Lube and the like with these cars. There are way too many horror stories. Even if you get lucky one time, there's a good chance you'll get the kid who knows nothing the next time.
Check the forum here for independent shops in NJ who specialize in MB cars.
http://www.peachparts.com/shopforum/new-jersey/