Changing fulid

[fantasticCG]

Right im changing my tubing and fluid colour as well as putting a drain port on my rig. What fluid will i need to wash out the system so i can put a new colour in?
Thanks

 

[fantasticCG]

Well basically I've got some dremeling to do
So it's all coming out and I want to put in a drain port,
So I don't have to keep cutting the tubing.