About Koyo RadiatorKoyo Radiators are designed, manufactured and specified to original equipment (OE) specifications. Koyo radiators are renowned for their OE style design made especially for import cars. Our NocolokR brazing line keeps the highest quality standards, bringing you superior products you can rely on. Koyo is Japan's largest aftermarket radiator manufacturer. The Koyo radiator is produced from aircraft quality aluminum and Heli-arc welded. Heli-arc soldering is the highest quality standard for enforcement along aluminum connections.