Koyo A13931 Koyorad OEM Replacement Plastic Tank Aluminum Core Radiator

The Koyo (Koyorad) A13931 is an OE-equivalent replacement radiator featuring a durable plastic tank with aluminum core construction, engineered to restore proper engine cooling on the 2021 Mazda 3 2.5L L4 with automatic transmission and turbo. Koyorad brings over 50 years of radiator manufacturing expertise, producing components backed by Japan's renowned cooling technology.

This radiator is built to match factory specifications exactly — from fluid tube count to cooling fin placement — ensuring a true plug-and-play installation with no drilling, cutting, or modifications required. It is designed to work with your existing fan shrouds, sensors, and mounting hardware right out of the box.

Key Features:

• Plastic tank with aluminum core construction for reliable OE-equivalent performance
• Engineered to meet or exceed original equipment (OE) standards
• Direct-fit replacement — bolt-in installation, no modifications needed
• Compatible with stock fan shrouds, sensors, and drain plugs
• Manufactured in ISO 9001 certified facilities
• Designed and tested to withstand years of under-hood heat cycling
• Backed by Koyo's industry-leading quality and fit standards

Koyorad's rigorous R&D testing and precision manufacturing process ensures each radiator arrives ready to perform. This is a cost-effective alternative to high dealer pricing without sacrificing quality or fitment.