Weird coolant loss in a Mk1 Fabia 1.4MPI

Quick update about the pressure test.

After around 18 hours of having the pressure test installed, the pressure went down to around 0.5 BAR as you can see in the photo:

And no drips under the engine whatsoever. I also checked all the connections and bone dry.

Removed the sparkplugs (as you can see they are in really good conditions) , removed the fuel pump fuse and cranked the engine, no coolant was inside the combustion chamber, so at lest in cold conditions, no coolant is going inside.

But that doesnt rule out that could be entering to the oil, and thats the only thing that i can think could be causing this problem.

A small leak that intensifies when as the engine gets hot and the coolant system gets pressurized.

Gonna study a little bit in how to proceed about changing the headgasket, do not like the idea of going head first in the repair without knowing what to do.

Any tips for this job will be appreciated.

Thank you all for your help by the way.

Gonna keep you updated with any news about this little thirsty engine.