Engine not getting up to temperature

[1fast6]

Since i changed the radiator for a new en and filled the system with some new type D coolant the engine never properly gets up to mid temperature.

Don't get me wrong, it goes just below the lower average bar but never seems to creep into the absolute middle.

Is there a problem or is it just the very cold weather this time of year?

Thermostat is deffo ok because i didn't open until it should have when i bled the system.

[Lunner]

Just the fact that you have a new rad and its working really well

[BRUN]

do you have a low temp stat in ?