I found this reply from Peter posted on another thread...
>>I am using Valvoline G-05 Concentrate mixed with de-mineralized water to a 50:50 blend. I paid about A$10 per litre for the concentrate. <<
Re "Evans coolant USA" it did not use any water at all. I seem to recall they claimed that once the stuff is in your engine there was little or no pressure in the cooling system due to its high boiling point..

They also claimed that it did not expand when reaching its 'freezing' point..
Aha!! found the site again

For more info take a look at ------
http://www.evanscooling.com/index2.html
PS. A small amount of the stuff was available in the UK. I dont know if it is now though..
.
James. (Nr M67 East of Manchester).
Dark Blue ZX 1.9D Auto 1994 'L' 5 dr (modified) Aura. 98K miles used daily. Ave mpg 40
Wedgewood Blue 75 CTD auto Connoissaur. 2002. 144k. used daily. ave mpg 40 ish.