Temp Gauge fluctuation warm up from cold start

[Lafetoo]

Those <40C above should be replaced by <60C, sorry for the mistakes

 

[megatr0n]

I am newbie here, just bought a 2015 E250 CDI FL(om651), my temp gauge has shown fluctuation symptom during first 15-25 minutes (15-20 km) of warm up, which goes up to 82 then drops back to 70 for 2-3 cycles before stick with 90 degrees, been searching weeks without a clue, dealer has changed thermostat under warranty but make no difference, dealer comment this is "normal".
I owned numbers of vehicle before, none of them behaved like this and took this long to reach optimal temperature.
Can anyone share their experience or is it really consider "normal" for mercedes CDI engines? or any fix /solution?
Many thanks

Hello, i am expiriencing the same problem on my w204 220cdi, the problems is there only when outside temperature is 15c or higher
Have you solved yours?
Regards

 

[Lafetoo]

Driving the car with this characteristic without any problem for almost two year since I bought it, I believe it was programmed this way by purpose.