HKS 4WD Transfer Oil Cooler Kit – Toyota GR Corolla

The HKS Transfer Oil Cooler for the GR Corolla GZEA14H is designed to control transfer oil temperatures during continuous high-load driving. The factory system switches to 2WD when the transfer unit overheats. This cooler reduces temperature, protects the transfer unit, and maintains stable AWD performance during track use.

What the Transfer Unit Does

The transfer unit sits behind the engine and redirects drive force 90° toward the rear wheels. The GR Corolla uses an electronically controlled coupling to fine-tune rear torque based on the selected mode (NORMAL, GRAVEL, TRACK). Under sustained load, the vehicle may reduce power to the rear wheels to avoid overheating.

Product Overview

The Transfer Oil Cooler helps prevent overheating and reduces limp-mode activation. It lowers oil temperature, extends oil life, and protects the drivetrain during track sessions. Vehicles equipped with the Transfer Protection Cancel Program can maintain full AWD even under high load. (Warranty impact may apply. Check your vehicle’s warranty terms.)

Compatibility Notes

• Japan models with cancellation program: Mar 2025+
• North American models with cancellation program: Aug 2024+
• Vehicles built Aug 2020–Dec 2020 do not have Transfer Protective Control

Components

• Transfer cooler pipe
• Oil filter
• Electric oil pump
• Pump controller
• Mounting bracket
• Hoses, wiring harness, and hardware

Key Features

• Pipe-type dedicated cooler that does not affect engine coolant, engine oil, or intercooler performance
• High-flow electric oil pump with overcurrent protection and automatic restart
• TRACK mode activation when used with the cancellation program
• Pump status displayed on the controller
• Banjo-type outlet fitting with PT1/8 port for oil changes or temperature sensors
• Bracket placement avoids blocking airflow to the radiator or intercooler

Pump Controller Modes

• AUTO: For vehicles without cancellation program
• FULL AUTO: For vehicles with cancellation program
• MANUAL: For maintenance
• Current monitoring and overcurrent protection
• Transfer protection cancellation (only for compatible vehicles)

Usage Notes

• Designed for circuit use; keep the pump off during daily driving
• Do not operate the pump when oil temperature is cold (below ~60°C)
• If the pump cycles on/off frequently, the oil is too cold
• Use OEM transfer oil or HKS G900 75W-90
• Do not use oil thicker than 75W-90
• Do not connect the 4WD mode switch if your vehicle is not equipped with the cancellation program
• Installation may require trimming of ducts or covers

Installation Notes – GR Corolla

• Trimming may be required on: bumper reinforcement, intercooler air guide, and undercover duct

Performance Testing

HKS testing at Fuji Speedway showed:

• Without cooler: oil temperature climbed to approx. 150°C+
• With cooler: temperature stabilised around 125–130°C

The difference under continuous load was approximately 80°C, significantly increasing reliability during long track sessions.

Installation Instructions

Download HKS Install Manual (27002-AT001)