What kind of paint goes on a radiator?

[belfert]

I had my radiator core replaced at a local radiator shop in 2007.  It sure looks like plain old paint on the core, but I don't really know.  I do know the cooling is 100% better now and I have no heating issues.

This same shop recently cleaned and tested my oil to water transmission cooler.  They didn't tell me they were going to paint the exterior of the cooler.  Whatever paint they used didn't adhere and came off in sheets.  I spent nearly an hour removing the paint where the hoses attach so the paint wouldn't peel off into the coolant.