Mixing coolant?

[v_forty]

Having changed the thermostat in the V40 over the weekend, the coolant level is now below the minimum marker. Should I -

a) top up with water (tap or bottle (hard water area)
b) top up with some spare coolant from a previous car (Holts brand, but almost definately different to what's in the Volvo)
c) buy Volvo coolant and top up?

[arcturus]

If it's been in a while why not drain and refill with fresh. Water will dilute the anti freeze capability. Some AF are specifically for the engine block material. I would not mix but maybe I'm just over cautious.

[Andy Northface]

I live in a hard water area too and judging by the state of my kettle,when I change my coolant for the winter,I will be using distilled water from the local car shop.I have a new rad' and I don't want it scaled up! Only a few quid and peace of mind.I agree with Acturus,i would also drain and re-fill for what it costs. :)

[940Graeme]

As above, yes definately - especially as we head towards winter - drain, flush and re-fill with at least a 50/50 mix. Not a difficult job, and you may as well get it right while you are there!

[RobbieH]

Have read including the linky in post #3

http://www.volvoforums.org.uk/showthread.php?t=134427