I have owned my October 2018 Octavia 1.5TSI from new and the header tank and coolant have not been disturbed. The coolant is clear and light pink. The header tank is marked G13 and is not marked mit Silikat. I have read numerous threads where people state the part number of their header tank and describe the coolant type marking and silica marking. However my header tank is 5Q0121407F and I have never seen a header tank with the F suffix in a thread. Does anyone know where my tank fits in tank evolution and if it contains silica?

Yesterday I have replaced my 5Q0 121 407 F with 5Q0 121 407 AA. I also haven't found any information about the F version anywhere.

The "mit silikat" marking wasn't there, but the G13 marking was, so I just replaced it to be sure.

Today I cut the tank open and it was completely empty. The only difference I found between the tanks is that the F version has the G13 marking and the AA version has no marking at all.

Maybe this information will help someone and they won't have to change the tank unnecessarily like I did.