Looks like the drinkable tap water in Sweden is harder (more minerals) than your system can handle. I would mix the coolant with purified/distilled water to avoid calcification in the future. Save the tap water for mixing drinks
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.