When a radiator shows micro-perforations, the first reaction is often to assume a manufacturing defect. In most cases, however, this is not the issue.
Stray electrical currents generated by poorly insulated grounds or faulty electrical components can trigger galvanic corrosion.
The result is localized and premature perforation of the fins or tubes.

Replacing the radiator without checking for voltage in the coolant means risking the same problem again within a few months.
For distributors: always point out this possibility to the customer. It helps reduce returns and strengthens your technical credibility.