Fill until it comes out the top plug. And yes.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Here's an interesting link discussing that the car need not be level for a proper reading of the fluid. I plan to raise only the rear of the car as Loubapache advocates in his post. Does anyone disagree--that it doesn't make much difference whether the car is level to get a correct fill?

http://www.peachparts.com/shopforum/showthread.php?t=29081&highlight=differential+fluid+capacity

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles