Distilled water and 33% M1 methanol.
-20 to -40 washer fluid works, but it has soap that will gum up nozzles and leave a crust in the intake.
Do not use food coloring to color the water, it will stain the intake. Just one drop of red per gallon turned the inside of my intake pink.
I use VP racing's 5 gallon pails a local petroleum company keeps in stock. Most race tracks and drag strips also sell Methanol by the gallon.