Does anybody have experience with testing and re-using
engine coolant?

After a very long time I need to pull the radiator out
of my Scout, get it fixed (leaky solder joints mostly)
and refill. The old coolant (conventional green Prestone)
looks reasonably good. The radiator is clean inside, the
coolant is clear. Specific gravity is low.

New coolant is more expensive than I remembered, and
getting rid (legally) of the old stuff is harder than
it used to be. Simply adding more antifreeze to make
the specific gravity correct is trivial, but I wondered
if there might be more sophisticated tests to detect
more subtle problems like pH. The original mix used
distilled water, so total dissolved solids are likely
to be OK. The major worry is the state of the corrosion
inhibitors. Ordinary pH test papers are subject to
cross sensitivity, so it'd have to be checked for
use with coolant. Web searches for coolant testing
found only specific gravity testers, nothing about
pH or other chemical tests.

Thanks for reading, and any stories!

bob prohaska