Yes the radiator is electrically insulated from the block and chassis via the shock mounts and hoses. Yes the radiator (cathode) and block (anode) are in contact via the coolant (electrolyte solution) which does plays it’s part in the rotting process. The evans stuff is probably better but I’m not familiar with it. Having the correct coolant for the metal combination and changing it regularly is important to limit the corrosion as coolant degrades in this respect. The voltmeter reading probably indicates that my coolant is way over due for a change which I will have to do soon as my rad is knackered (again).
Does it matter? Probably not (at least for a long while) as the internal block corrosion would be very slow on the large metal mass. Long term through it is another good reason to replace my rad with an aluminium rad and eliminate the process altogether.
Keep your fingers crossed re the gazelle
