...But I guess you don't know what they have in the pre mixed stuff either.
1) PEG (or EG for the cheaper green stuff, which by the way has better "cooling" characteristics than PEG, but w/e...)
2) Distilled or deionized water
3) surfactants (like WaterWetter) - basically a chemical "soap"
4) Lubricants - soluble oil or similar slightly polar product
5) Corrosion inhibitors - like silicates (dissolved silicon/metal salts, not sand
) or carboxylates (newer tech, but not great) or 2-EHA (new, horrible stuff)
6) pH buffers. Basically, other salts.
7) dye (maybe)
There is NO
rocket science behind this stuff.
The chemistry (not that anyone asked...):
* Start off with distilled water (using the DI stuff straight in the rads will ruin your cooling
system in short notice, but you can make
it with DI if you buffer it properly later)
* Add surfactant to maximize Q (the ability to move heat from the engine into the water). A little goes a long way.
* Add PEG (purple) or EG (green) until the water doesn't boil at the high end of the operating temp/pressure in the bike. (cold weather formulas are slightly different)
* Adjust pH (basic) so you don't cause electrolysis in the engine or rads
* Add pH buffers so the pH doesn't change over time (add silicates...)
* Add some soluble oil so the water pump doesn't seize
* Add dye to make it pretty if need be
It's really a straightforward process and pretty much anyone can make the stuff in their garage for pennies. The proportions are "proprietary", but if you think about it, you can't put too much or too little of anything on the list or the product won't cool properly, so they're pretty much all "about the same" (well, all PEG/water blends are about the same as other PEG/water blends, and EG/water blends like other EG/water blends, and even then
the cooling characteristics aren't that
much different between the two families, just the boiling points and things like toxicity, viscosity, which are pretty minor factors, generally speaking). If we think someone's product is better than the next, us sheep will buy the "better" product. We're just human that way!
The thing that makes me nervous about using "some guy's recipe" is if they don't use enough commercial coolant. You need enough of that stuff to minimize corrosion and lube the pump unless you add your own lubricant and buffers. It's kind of a big deal to run a dilute mix because the silicates can get used up quickly and start to fall out of solution (scale). Dilute solutions should be changed more often because of that.