a little bit of glycol or an anti-corrosion/water pump lubricant like "Water Wetter" (which is useless when used with normal antifreeze concentration).

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Obviously, a glycol/water combination with water pump lubricant and aditives will corrode less and cool better than water alone.

I do not dispute that water wetter is useless with normal mixtures, but it would be useful to know why.

Water wetter, of course, does not say that it is useless to what must be most of the people most of the time, I imagine for obvious reasons.

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Semibodacious Transmogrifications a Specialty

1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

"Time flies like and arrow, yet fruit flies like a banana"
---Marx (Groucho)

Psfred pointed out the very important reason (besides corrosion protection) of using the proper coolant mixture for summer. Once boiling commences, the thermal transfer properties of the coolant are ineffective. You need the coolant to not boil for effective heat transfer. I believe steam has 1/13th the thermal transfer properties of water.

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95 E320 Cabriolet, 159K

Commercial anti-freeze mixed with water has everything needed to prevent corrosion and protect the water pump seal. Like motor oils, you do not need supplemental additives when you use a proper concentration of antifreeze and water.

I've never been able to figure out exactly what is in Water Wetter, but there's a chance that it may have some incompatibilities with some antifreeze additives.

It's probably a good idea to use it in a race car that uses straight water as a coolant, but I do not recommend it if you use a proper antifreeze and water blend for the above reasons.

Duke