Sacrificial anodes are not easy to use on cars. Ships....easier due to size for fitting etc.
Avoid copper!
Early Aluminium window frames were made from duralumin, Al/4%Cu alloy. They corroded badly, especially in coastal areas.
The key to sZcrificial protection is the quality of the bond or connection to eZch metal, the electrochemical process needs this. A bit like corroded earth connections as an analogy. Poor contact = poor result.
For protection of the coolant system just use the correct antifreeze...simple solution (excuse the pun).
