Hello. Ride 2.0 TDI CBDC year 2010 with manual transmission, 185000km. In the winter months I have to notice more and more that the coolant indicator under partial load falls back again and again. At mountain descents even further. Is this normal or thermostat not working perfectly? If the DPF regenerates it remains constant at 90degrees. On the highway there are also no fluctuations. In summer there are also no problems! Is it harmful for the engine when the thermostat no longer completes?