Coolant additives

[crankedup]

Neither of my pre 1930 cars has any form of additive in the water that might assist to keep the waterways from clogging. Would it be worthwhile to add such a product and if so any recommendations please. I currently use filtered rainwater in the radiators.

[garethj]

It's always worth adding corrosion inhibitor, even if your car has an iron head and copper/brass radiator as it can corrode through the copper tubes.

I've no idea which one though. Can any of them do any harm (other than making it more likely to leak a bit)?

[Wombat Rick]

Millers stuff is always good. You could try their "Extra Cool".
http://www.millersoils.net/M3_cgi/millers2.cgi?pro...