There is an easy way IMO: replace the coolant at the recommended interval with the correct coolant.

As far as the Subaru thing, other than the poor spelling, I have to agree with others that it sounds contrived and the battery's proximity has nothing to do with the corrosion inside the cooling system.

However, if the engine had a poor ground to the body, and the battery were grounded directly to the engine, it is possible that there would be a different potential at the engine and body while driving/charging, and that could lead to additional corrosion. This doesn't appear to be what the Subaru blog was about.

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Gone to the dark side

- Jeff