[TR] winter time

[FRED E THOMAS]

Easy way to check for radiator corrosion protection, just as important as
checking the antifreeze, if the coolant is allowed to become "acidic" the
engine and radiator will also become corroded with rust. Using a volt-ohm
meter (VOM) set it to a DC voltage range that measure in "tenths" of a volt,
remove the cap and place the negative VOM lead into coolant, being very
careful not to touch any other part of the radiator. Place the Positive lead
of the VOM against a bare metal part of the radiator (or a good ground of the
engine), a reading of 0.2 volts or less, coolant is in good shape, a reading
of 0.5 volts it is borderline, 0.7 volts replace your coolant immediatly.
This comes from my "Model A" workshop manual and also says it works in modern
cars as well, which is really more important because of aluminum heads or
dissimilar metals in modern cars.