On my Prius the spec is 5000/6 months, and my former truck was 10,000/6 months. So they get/got changes every 5000 no matter the time. Sometimes that was 4 or 5 months, often it was 8 months. Sent a 9 month 5,000 mile sample from the truck to Blackstone who found no issues but did state based on the sample that 5,000 was a good interval.
If you really want to know spend $25 to send a sample in for testing.
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!