1.8T ( 20 V. ) , Engine can't maintain normal operating temperature.... ?

[2stroke]

I have a problem, my 1.8T ( 20 Valve ) can't maintain normal operating temperature during normal winter temperatures.

I have changed the following parts 3 !!! times, but no difference.
* Thermostat
* Sensor G62
* Sensor G2

What could be wrong when the engine is unable to maintain normal operating temperature ?
( ....bad Thermostat you think, but since I have changed it 3 times I have ruled that out )
I have also logged the oil temperature with VCDS and I also think it is too low ( which also indicates that the cooling water in the oil cooler has too low temperature )
There are no error codes.
No leaks.


HELP !!