I understand how to filter mixed fluids with Fluid filter, but how to mix them first? If you try to put any pipe witch connects different fluids, game shows error, that can't connect systems with different fluids.
How you did that in the example picture, where you mix all three fuils form the Refinery?

I second this. I have no idea how to make this work.

Alright, I get it. It's a part of his "Fluid Mixer" mod, and it works only with vanilla fluids.

it also works with his other fluid mods I think you will find

if you try to mix with anything other then your hand (robot places the pipe, machine get recipe after pipe is placed, ect the fluids will mix)