[gearboy]

Anyone know the reading range when using an ohmmeter to monitor electrical properties of engine coolant as measure of the coolant's health? In other words, below such-and-such OK, between such-and-such marginal, over such-and-such, time to change coolant. Would the baseline be different for soft water and a good quality corrosion inhibitor like No-Rosion or Redline vs. water and antifreeze? Anyone using this test?
We tried it 20 years ago in one of my cars, but as we moved the meter's test probes in the coolant, got varying readings and gave up. [color:\\"black\\"] [/color]

[bkazmer]

I haven't heard of this technique before, but you are measuring the conductivity of the coolant, so additives and hardness(metal ions) will be driving the value. When you need to check the quality of deionized water, you measure the conductivity.

[ashgray2]

I heard about this but this is available for digital driven cars.
It is a USB device that can be plug to your laptop then connected directly to a circuitry of your car.

It measure car engine temperature and also the limit temperature of some engine parts.

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[OldsmoREO]

An accurate test to determine the viability of your antifreeze is to attach the positive lead from a digital volt-ohm meter to the metal part of the radiator, then center the negative lead into the coolant itself. A voltage reading of 0.2 or less is very good. A reading of 0.5 should be considered borderline, while anything over 0.7 is unacceptable.
If your coolant fails this test the coolant system should be drained and flushed and fresh antifreeze should be added.
There is a new generation of "lifetime" antifreezes being promoted. Do not mix these with the ethylene glycol antifreeze that has been in use for the last sixty years, as they are not compatible. I do not recommend using lifetime antifreeze in collector cars. I understand that it will seep everywhere, including into the cylinder areas, in cars not assembled with the newer rubber bonded steel gaskets.