Anybody ever hear of testing coolant this way.

If the coolant's age or condition can't be easily determined, there is a quick check for coolant contamination using a Digital Volt-Ohm Meter (DVOM). Attach the positive DVOM lead to the radiator, then dip the negative lead into the coolant at the filler neck.

A voltage reading of 0.2 volts or less is very good. A reading of 0.5 volts should be considered borderline and anything over 0.7 volts is unacceptable. If the coolant fails this test, the cooling system should be thoroughly flushed and cleaned. Remove any engine temperature sensors and inspect them for contamination or other damage. Repair as necessary.

From the www.borg-warner.com site.

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Jim