I think I have my answer after a long discussion with Bill, who was, or is , a Telstra electrolysis expert in Melbourne .
Don't worry about the radiator. I could put an ampmeter in there to test, but if it read high then I would be better to deal with the cause rather than putting in an anode.
Regarding the wings-Sacrificial annodes do need an electrolyte to work, so the suggestion that as my car is not a ship in saltwater then anodes will not work is correct ...at face value.
But, there is electrolysis on the wings of my car, therefore I must assume that wet drives, and moist nights , provide enough medium for electrolysis to occur between the aluminium and steel wire . It is fair to assume then, that wet drives and damp nights will provide a medium for a sacrificial anode to work if correctly stuck on the car.
Magnesium is further up the scale of whatever than aluminium, but too far up, and could damage the wings. Zinc should work fine, the aluminium should slightly passify? against it, and hopefully, any electrolysis will sacrifice my anode.