Skoda Octavia MK2 1.6TDI Thermostat Replacement

Hello all!

I have a Skoda Octavia MK2 1.6TDI (CAYC) with 161k miles on it.

The last couple of months I've noticed my coolant temperature fluctuating. When on short trips it slowly heats up but when on the motorway it would go down to 0.

Fuel economy is gone very poor with averaging 40mpg when prior I was achieving 55-60mpg.

I've narrowed down the issue to the thermostat and have got a replacement Febi Bilstein thermostat with the housing.

I've watched some videos on replacing it and have got mixed info and was wondering if anyone has any experience with this repair and if so any tips or tricks on the matter?

Thanks in advance

-Josh