Review on Denso 221 3213 Radiator by Chad Blanchet

I just received this radiator from stock and installed it on a 2001 Honda Accord ex v6 3.0L. Two days later I noticed that the gear oil was empty and I just added 3.5 liters. Same problem occurs again and I couldn't find where it was leaking from as I didn't notice anything from the coolant line hoses. The lower radiator coolant lines appear to be the culprit although they have been tightened fairly well and the transmission to the coolant hoses is fine with the clamps tightened. Eventually the mechanic told me it was leaking from the radiator coolant lines and he said it wasn't a genuine Denso part as it had aluminum radiator lines instead of bronze like my old radiator. Can anyone tell me why this happens with a new heatsink?