HKS Oil Cooler Kit – Honda Civic Type R (FL5)

HKS Oil Cooler Kit for Honda Civic Type R (FL5) is engineered to support sustained high-load driving, including continuous use of +R mode and circuit driving. Developed specifically for the FL5 platform, this kit applies HKS’ proven heat management philosophy to address oil temperature rise under demanding conditions while preserving overall vehicle balance and factory aerodynamics.

Overview

The FL5 Civic Type R represents a significant evolution over the FK8 in terms of chassis performance, power output, and aerodynamic efficiency. However, extensive road and endurance testing by HKS identified oil temperature control as a limiting factor during prolonged high-load operation. This oil cooler kit was developed to resolve that weakness, allowing the FL5 to deliver stable performance for extended periods.

Building on the proven FK8 layout, the oil cooler core is mounted inside the left fender to avoid obstructing the radiator. The system has been completely re-optimised for the FL5, taking into account cooling airflow, water temperature interaction, and air conditioning performance.

Cooling Design & Airflow Management

Wind tunnel testing revealed that the factory front bumper alone does not supply sufficient fresh air for effective oil cooling under high load. To address this, HKS designed a large, FL5-specific air duct and dedicated air guide that actively channels fresh air directly into the oil cooler core.

Equally important is controlled air discharge. Repeated airflow testing ensured that heated air exits smoothly after passing through the core, preventing turbulence and maintaining optimal airflow throughout the system. An outlet plate is included to protect the core from stone damage and debris.

The result is a highly efficient system that suppresses oil temperature rise even during aggressive circuit driving, while also contributing to reduced water temperatures.

Performance Results (HKS In-House Testing)

• Oil temperature reduced by approximately 15°C compared to the factory oil cooler
• At 26°C ambient temperature, oil temperature stabilised around 125°C
• Factory oil cooler exceeded 140°C without stabilising
• Water temperature reduced by approximately 3–5°C due to non-obstructive fender-mounted core

Key Features

• Fender-mounted oil cooler core for efficient cooling without blocking the radiator
• FL5-specific large air duct and air guide to maximise fresh air intake
• Smooth air discharge design for optimal system airflow
• Outlet plate to protect the core from stones and road debris
• Thermostat-equipped system for controlled oil temperature management
• Designed for high-load street driving and circuit use

Kit Contents

• Oil cooler core
• Resin air duct (unpainted)
• Air intake duct
• Outlet plate
• Mounting brackets
• #10 oil hoses
• Thermostat housing
• Oil filter
• Installation hardware

Optional Components

• Dry carbon air duct (clear coated with metal mesh)

Installation Notes

• Bumper and splash shield modification (drilling) required
• Estimated installation time: approximately 6 hours

Vehicle Compatibility

• Honda Civic Type R FL5 (K20C) – 2022 onwards

Technical Specifications

• Core size: 200 × 122.5 × 48mm (9-stage)
• Core location: Inside left fender
• Hose size: #10
• Air guide: Resin (standard), carbon optional
• Code No.: 15004-AH105

Related Maintenance Items

• HKS Super Zero Racing Oil 0W-20
• HKS Super Oil Premium 0W-20
• HKS Oil Filter Type 1

Installation Instructions:
Download PDF Instructions