I replaced my radiator tonight with an aftermarket Denso (made in Indonesia). It looked just like the OEM (plastic/aluminum), but it had a single saw cut on the top similar to the picture of the Koyo radiator. I would have preferred an all aluminum radiator, but couldn't really tell when I ordered the Denso whether it was all aluminum or a combination. Hopefully, the cut helps solves the early failures on these radiators. Other than some of the hose clamps, it wasn't a bad job at all.

 

I don't see how when most of the failures were at the bottom of the radiator.

 

I'm not sure about the others, but mine appeared to be failing at the seam where the plastic is crimped to the aluminum. Since the radiator is secured to the vehicle via the plastic portion, I imagine as the aluminum expands it puts pressure against the plastic. It could also be an issue of the aluminum being more tolerant to warping than the plastic. Not sure, only theories.

However, it appears Denso decided a change was needed from the original design. It seems logical this change was due to the high number of failures in the original. But since I don't work for Denso I can only speculate. Not that the swap was too difficult, but it would be nice not to have to worry about the radiator again.