The filter from the R230 fits exactly into the R231. A003 184 61 01. According to specialist companies, you should change the filter every 20,000 km. I made it today with my R231 500. 0 problems. In the container 1.5 liter oil is present which should of course be changed. According to specialized companies, the ABC suspensions hold approx. 500,000 km if you make the change. Help Free the problems have when changing. The filters are available at many companies ( Goggel ) and are snow-wise. Peter