I use Tectaloy 100 which is green and pre-mixed. Also did a fair bit of research before selecting this one. It was between the Nulon and Tectaloy.
With the Alloy rad etc... I use green. No brass monkeys in my system - Tee Hee.
Nissan are now using Blue - FTW
Some are just died because it differentiates between GM, Toyota, Europee'n and US cars.
There is Red, Green, Orange, Yellow, Brown and now Blue.
They used to colour them for a reason. 3 different types - Oats, Hoats and another one.
Now it's all just pretty *rainbow*