I have a pin-hole leak in the top of my radiator near the upper hose. I put the steel wool to it and, now have it down to bare metal...and a tiny hole with hairline crack is visible.

So my choices are:

A..plumbers solder- low melting point, but not a strong material. Doesnt build up a cap very well either

B..braizing rod- high melting point might cause damage to radiator, but will easily cap off a hole this small

C..the newer stuff like staybrite 8 - supposed to be good stuff (when used for copper tubes to brass)
fairly low temp but durable

I wonder hot I can get this metal ?
What do repair shops use? Does anyone have a clue about these radiators?
It's marked Denso- I guess it is the original one