Hello! Volvo V40, 1.8 85KW, year 98 With my V40 I noticed with the falling temperatures that the coolant temperature indicator fluctuates. The engine became (feeled) warm in normal time, however, the temperature pointer fluctuated downhill during longer rides and finally also in flat terrain with moderate load of the engine. This pointed for me to an age-weak thermostat. So it was changed fixed and immediately the cooling liquid renewed. The ventilated was as follows: Fill up coolant, heat up fully, let the engine warm up, with lack of coolant pouring down, drive a few kilometers and let the engine run until the switch on the cooler fan. Motor out, let cool down and refill again. Since then the coolant level has not changed any more. Since then the engine is only slowly warm. On the road I get it on about 1/4 of the scale, in the town of the manufacturer in traffic jam the display rises then to 1/2. On the Auotbahn it also rises to 1/2. In this position it remains then too. The thermostat can vary slowly?