Originally Posted by Roelof

It takes a while that the engine is really warmed up. I have a clear telemetry readout:
https://www.youtube.com/watch?v=cwkVENYaK-k

On the right in the graph and right under is the temperature readout. The engine was pre-heated to almost 80 degrees C as you can see on the digital meter. From running the 1st lap (1:20 Youtube time) it took 2 minutes before the temperature goes up beyond the 80 degrees C. At 4:20 I do a practise start where you can see a huge raise of the temperature when the car is standing still. That is where the cooling stops and all the heat will concentrate in the engine.