[Alan Roehrich]

Go to your Cadillac dealer, and get yourself a card of the coolant supplement pills they carry. Those pills are specifically made to keep dissimilar metals from eating each other.

As far as water goes, you have to find something that isn't full of chlorine.

There are companies that sell "sacrificial anodes" that you suspend in the tank of the radiator, under the cap. The anodes will sacrifice themselves to the corrosion and electrolysis, so your engine parts are spared. At least to a degree.

Also, make sure you have plenty of good ground straps, and all your connections both positive and negative are good. Using the engine to conduct electricity causes corrosion, especially with the dissimilar metals.