We, John and me, have been wondering if there is a way, (a test kit would be
excellent), to test coolant for adequate levels of additives.  There is no objective
argument we know of to support changing the coolant if:  it still retains the
original color, is close to a neutral ph, and still has a sufficient amount of the
additives package.  No apparent reason to discard coolant that has been mixed with,
and topped off with, distilled or a low 'dissolved minerals' containing water no
matter how long its been in use as long as it passes muster.  Specifically the two
categories of additives are the water pump lube and the 'anticorrosives'.  A test
for neutral or above ph, >6.9, is a good thing to do also, and it probably is
important not to have it excessively alkaline, (say above 8 or 9?), or excessively
acid.

At the moment I'm using NAPA's 'number 13'.  It's a 12oz. bottle that claims it
"...stops rust and prevents electrolytic or "battery" type corrosion.  Prevents wear
on all types of coolant-lubricated water pumps.  Contains no silicates."  The
ingredients are:  petroleum oil, sodium petroleum sulfonate, nonylphenol
polyethoxylate, and water.  I'm guessing the petroleum oil and sodium petroleum
sulfonate are for the water pump and the nonylphenol polyethoxylate is for
corrosion/electrolytic prevention.  This nonylphenol polyethoxylate might be the
item we would most like to check for.

The bottle reads: "For over 20 qt. capacity use two bottles."  I give my vehicles
the 'bottle prescribed dose' every two years since that is what the majority of
coolant manufacturers recommend as the change interval.  I've been doing so with the
same coolant for six years now and have not yet had to replace a water pump.  Any
corrosion in my engines is tough to know, but my heaters still work well; the
engines don't overheat.  I've read somewhere that too much of a good thing is
possible here and may have detrimental consequences, (can't remember specifically
what), so I would stick with two year intervals.

Comments please.  We would like to know if there is something we have failed to
consider here.
-Dana-