Water Wetter DOES work in specific cases.  It
does nothing for the thermal conductivity of the
water.  It is, as John said, a surfactant.  It
makes the water "stick" to surfaces better than
it would otherwise.  So, for instance, if you
have localized boiling at a certain part of your
cooling system, this stuff will raise the temp
of that localized boiling because the liquid
water will stick to the surface better.

If your cooling system works well and you
don't need any help, don't use the product.

If things are marginal (old system, old
engine, high power, hot conditions) then
dump some in, by all means.

Redline (mfg. of water wetter) also makes
excellent synthetic lubricants which many
of us use in our transmissions.

tabe johnson/87 westy