Sorry its hard to have stuff come into your head, then write it out in some legible form.

Most of those premix bottles say to use distilled water, it has just been demineralised.

Yeah I think I'll just get the recovery bottle going. The point to me not using one was not because it didn't come with one just I couldn't be bothered. Thanks for the advice! Am so curious as to why this is happening though! It is Bmw coolant tht I use, dont see how that could be causing it though!
Cheers Ed

Distiled water has a higher boiling point and is les corosiv. so would be better than just tap water, but I think as sone as is get's impurities in it it's just plain water again I think, so you would need a bloody clean water system for it to do anything??

tried emptying the radiator and just using the premixed stuff?

And back when Dinosaurs ruled the earth,a half a cup of Kerosine was added to the radiator tap water to lift the boiling point and as an anti corrosive agent.

You've had good advice from the guys,now go implement it and report back.

EWWWW premix!
Stay away from that stuff I make my cordial stronger than that stuff is mixed. Always mix your self!

pre mix is good for testing the system before pouring $30 antifreeze/boil in there though, and thats it.

When you put it like that I agree

second that one....