i had the same problem with my E320. Same engine but anyway I use a ton of oil and I bought the car used from the dealer. I ekpt on takin it back and they said it was normal to use 1-2 quarts of oil every 1000 miles. I was like WTF??? SO i called MB-USA and all they did was give me a hard ass time before the gave me a new engine for free because this is a common problem with the 320 engines