This is equivalent to an 'octane booster' for your fuel tank. These manufacturers package a higher content of additives into a smaller bottle that is already included with the coolant or fuel. If you want to blow $10 then dump their magic pill into your radiator or gas tank. I read Redline's tech info .pdf and their claims are so miniscule and common industry knowledge it won't get them sued. Basically this stuff consists of (duh) a wetting agent (intermixed with the term surfactant), deionized water and a defoamer (some wetting agents can foam like a mufu). Regular antifreeze manufacturers already put in their own wetting agent and dispersants to make the dispersion stable so glycol won't separate or settle out from the water. Their main concern is that the dispersion not go to crap on store shelves and inside your engine, so surface tension is not a significant concern. Redline and these others just put the emphasis on surface tension to get you to spend $10 for something they want you to think is something so

very important.
As a chemist, here's my caveat as to why I don't use these fuel and coolant additives: wetting agents are notorious for being incompatible with other wetting agents. What I mean by incompatible is that one wetting agent can turn another wetting agent useless causing separation and/or settling within the antifreeze. It's like when your great-great-granddad tells you not to mix engine oils when you top off. Most engine oil manufacturers test their oil compatibility against other manufacturers nowadays plus they are regulated by federal standards. However, these upstart additive companies mostly do not compatibility test due to expense and there no G-men requiring them to do so.
So, in my humble opinion, if you follow your maintenance schedule on your coolant flush and fuel filter change you'll have no need for these materials. You'll see the advantages Redline is already claiming just by doing the normal.