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Subaru WRX STI (2015–2021) Radiator & Cooling FAQ's

Please read our FAQs page to find out more.

What cooling upgrades address STI heat‑soak on track?

An aluminum radiator, auxiliary coolers, upgraded fans, and silicone hoses improve heat shedding. Proper shrouding keeps the core fed with cool air.

Is an oil cooler recommended for a tuned STI?

For repeated high‑load use, yes—an oil cooler stabilizes viscosity and pressure so the EJ257 maintains a safe film at temperature.

Do I need to bleed the STI cooling system after upgrades?

Yes—follow the correct bleed procedure and verify fan operation. Air pockets create hot spots and fluctuating temps.