The website of Evans, a retailer of this stuff, contains an assortment of pseudo scientific stuff.

It claims their product is better at cooling at hotspots because water forms steam at these points. It doesn't mention that the latent heat of vaporisation of water is about 536 calories per gram, which is heat that has to be absorbed from the hotspot to turn the water into steam.

Another line uses 'viscous' when the word should be 'vicious'. I would be tempted to regard the stuff as a variety of snake oil; I am willing to be convinced if anyone has genuine independent evidence of real benefits for ordinary car users.

plus you had the additional advantage that it didn't leave any deposits like water does.

Dirty water?? ;)

I read somewhere that manufacturers now use distilled water in their cooling systems - presumably to get rid of limescale/mineral problems. Dont know if thats true though.