You still don't need the always on mod; you just need to SEE the flow. The additional reservoir allows you to not only SEE the flow, but allows you to have completely different coolant fills, and you can easily check the IC circuit fill level to see if your IC is starting to leak. I run a 75/25 fill in the main engine coolant circuit year round as we rarely see 33deg.'s here. And in the IC circuit I run distilled water and a bottle of water wetter from Rob.