[77newell]

If Atlas had a problem you would have to be wildly unlucky to keep getting the bad ones while no one else getting replacements is having trouble.

There is one way this could happen, assuming it's a dissimilar metal issue is if there is a small current flowing through the radiator, there should be none. A way for this to happen would be if you have a coolant sensor that has a ground wire that isn't properly grounded. Then when moisture is present it is probably that corrosion will take place. I don't know if this is the cause of your situation but I do think that seeing how any grounds are hooked up and making sure that current does not flow through the core to get to ground.