The very thin horizontal cooling fins in my (94 corolla) Radiator are
disintegrating and dropping out, and are very brittle.

The upright tubes carrying the coolent in the radiator still seem o.k. This
radiator i bought new about four years ago, admittedly quite cheap, but
should it be doing this?

where it has gone brittle is in two large patches that have lost the black
paint the radiator is painted in. if i were to respray those areas in a
black cellulose might that halt the rot, or what else to do?

Grateful for any advice. thanks john west.