Join Date: Feb 2013
Location: Aussie in Sweden
How low is the coolant level? Is it just below the minimum mark or is the expansion tank virtually empty?
If its not that far below the minimum mark just use demineralised water to top it up (should be less than 1L) and get around to doing a full flush in the near future.
Colour matching is not an exact way to know you are using a coolant with the same chemical makeup and it can potentially cause issues, though that is unlikely. So personally I would avoid it if you can. Topping up with 1L of demineralised water shouldn't raise the freezing point too high, especially with winter behind us, and would be the recommended way to go (I had to add about 750ml of demineralised water when I bought my 156 the other week and its freezing point is still -30).
If the level is alarmingly low; grab 1L of blue coolant and some demineralised water and top it up in a 1:1 mix.
Either way I would recommend you change the coolant as soon as possible. Its not a hard job to do and would probably only take you an hour to do yourself and you don't even need to jack the car up if you can manage to get the under tray off and use a slim oil catching pan to catch the coolant (remember to dispose of old coolant legally). Just make sure you give it a really good flush and then replace the blue coolant with a red OAT (organic acid technology) long-life coolant as they last longer and do a better job at protecting from corrosion.
2000 Alfa 156 Sportwagon 2.0 TS CF3
2002 Alfa GTV 2.0 TS CF3
1983 Porsche 944