mjhawkins2346

The recommended interval is 10,000 or 12 months for oil changes. The engines are amazingly picky on the oil you use. The only 229.5 spec oil I use is Mobil 1 Euro Formula 0-40 which is preferred. The only Mobil 1 5-40 is the "M" formula oil. Look on the bottle to make sure it is a 229.5 Mercedes spec oil. The 0-40 might give slightly better mileage. Here is the link;
http://bevo.mercedes-benz.com/bevolisten/229.5_en.html
I just changed the oil on my 2010 GLK350 4Matic at 9100 miles on the oil and filter and sent a sample to Blackstone. They said it look great and still had some additives (3.7) and the 10K interval seems to be doing fine.
Send your oil in when you change it to establish a baseline. It's saves money and your engine to be sure. A $35 well spent.