Grounding question

This is NOT correct. The OPPOSITE is true. You want the BATTERY, the BODY, and the ENGINE all as close to each other as possible. One good way is to get a "starter" (ring to ring) cable in say, no4 or larger, bolt to the rear of the driver side head, and then to a bolt through the body or to one of the master cylinder mounts.

Electrolysis is caused by chemical action IN the coolant, caused by the coolant itself and the materials in the engine and radiator itself. In other words the material in the engine and radiator, together with what is in the coolant, turns it all into a battery. I "ain't" an expert on this, but there are various coolant additives to modify the coolant and prevent same. Over the road trucks use this stuff.