1 of 2
Skip to product information
1 of 7

Mishimoto 12-15 Honda Civic Si Performance Radiator

MISMMRAD-CIV-12SI

Regular price $399.95
Sale price $399.95 Regular price $440.00
Request Price Match

Out Of Stock, Backorder Now.

Awaiting stock, shipping soon

  • Fully secure checkout
  • Trusted by thousands
  • Rated and reviewed

Upgrade the cooling system of your 2012-2015 Honda Civic Si with this Mishimoto Performance Aluminum Radiator, built to manage the sustained thermal output of a high-revving K-series engine on the street and the track. All-aluminum construction with precision TIG-welded end tanks outlasts the factory plastic-tanked unit prone to cracking under heat cycling and repeated high-rpm use. A 63% increase in core volume over the OEM radiator delivers greater surface area and thermal capacity, keeping coolant temperatures stable during back-to-back pulls, spirited street sessions, and weekend track days where the stock radiator starts to fall behind.----Designed as a direct-fit replacement for the 2012-2015 Honda Civic Si, this radiator drops in without cutting, fabricating, or modifications, and works seamlessly with all stock hoses and components without alteration. The included high-pressure radiator cap maintains optimal system pressure from the first drive, extracting the full benefit of the upgraded core. The Mishimoto Magnetic Drain Plug catches ferrous metallic debris before it circulates through the cooling system, protecting your K-series engine internals and extending service life beyond what the factory setup allows.----Don't wait for your stock radiator to crack and leave you sidelined. Whether you daily drive your Civic Si, push it hard on weekend canyon runs, or are building toward a higher-output K-series setup, this aluminum radiator handles the sustained thermal demands your factory unit was never built for. Proactive cooling upgrades protect your engine investment - and this one is built to outlast it. Backed by the Mishimoto Lifetime Warranty, this Performance Aluminum Radiator is the last cooling upgrade your 2012-2015 Honda Civic Si will ever need.

Installation Instructions
MPN: MMRAD-CIV-12SI
⚠️ Proposition 65 Warning: This product may contain chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm. Learn more »
Mishimoto 12-15 Honda Civic Si Performance Radiator

$399.95

FAQ

When does my order ship?

Most orders ship in 1–3 days, but some items may take longer due to demand and manufacturing delays. For urgent orders, please contact us to confirm stock before purchasing.

Are returns accepted?

Not satisfied? Return any item within 30 days. See our FAQ page for details.

Buy now pay later options available?

Yes. Pay later in installments with Affirm or PayPal Pay Later.

Do we offer price matching?

We’re happy to price match any legitimate listing from an authorized dealer, as long as the item is in stock and the price is current. We cannot match outdated or incorrect discounts based on old MSRP, since those prices are often errors the competitor cannot honor.