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Optimize Your Subaru's Cooling System Without Breaking the Bank!

Let's face it - engine cooling technology can sometimes seem like a dark magic that is impossible for us mortals to understand. That being said, it is well known that raising the pressure in your cooling system has a direct correlation to cooling performance. The factory 1.1 Bar (16 PSI) cap performs fine for daily driving with a system full of anti-freeze, but for those who are looking to push their Subaru harder or run on the track may be running an anti-freeze/water blend (or in many cases just straight distilled water) as it provides better heat transfer and dissipation than your standard coolant or antifreeze. The downside to running water or a blend of antifreeze/water is a lower boiling point and thus you would easily fill up (and in some cases overflow) your expansion tank within a couple of hot laps.

Upgrading the radiator cap to one with a higher pressure rating is the easiest (and by far the most economical) solution for solving this issue and keep your cooling fluid of choice where it belongs - in your engine and radiator. The GrimmSpeed High Pressure 1.3 Bar Radiator Cap is a high quality and way to maximize your cooling systems potential and upgrade the looks under your hood without breaking the bank!


  • 1.3 Bar/18.9 PSI Pressure Rated
  • Increases Cooling System Efficiency
  • Electro-coated Stamped Steel Construction
  • Heavy-Duty Silicone Seal
  • Understated Look Eliminates Ugly OEM Yellow Badge
  • Manufactured in Japan


  • All Subaru Radiators and/or Expansion Tanks
  • Many (but not all) Nissan, Mitsubishi, Honda, Mazda, and Toyota Models

*fitment note - not suited to replace the 1-way "earless" cap on the STI radiators, but will work perfectly on the upper expansion tank!


Installation couldn't be easier! Just twist the factory cap a little over half a turn counter-clockwise with remove and replace with your new GrimmSpeed Cap!

Ensure that your engine is cool before installing. Never remove your radiator cap immediately after driving your vehicle!

1 Review

Jared Davis 12th Nov 2023

Love it

The cap looks amazing underneath the hood with the rest of my Grimmspeed product. It's also holding the pressure really well. I would recommend this product.

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