Protect Your GR Corolla’s AWD System Under High Load

The HKS Transfer Oil Cooler Kit is a dedicated cooling solution engineered specifically for the Toyota GR Corolla’s AWD transfer unit. Designed to monitor and actively control transfer oil temperature during sustained high-load driving, this system helps prevent overheating that can force the GR Corolla into 2WD mode.

For serious drivers who track their car, run canyon roads, or push extended high-speed sessions, this is a drivetrain protection upgrade — not just a performance mod.

Why This Matters for the GR Corolla

From the factory, the GR Corolla’s AWD system will automatically reduce rear drive engagement and switch to 2WD when transfer oil temperatures become excessive. This is a built-in protection strategy to prevent damage.

The HKS Transfer Oil Cooler Kit:

• Reduces transfer oil temperatures
• Extends oil life
• Helps maintain AWD functionality under sustained load
• Protects the transfer unit from heat-related stress

In real-world testing at Fuji Speedway, vehicles without the cooler saw transfer oil temperatures exceed 150°C and continue rising. With the HKS cooler installed, temperatures stabilized around 125–130°C — a dramatic improvement under identical conditions.

That’s the difference between thermal shutdown and controlled operation.

What Is the Transfer Unit?

On the GR Corolla’s AWD system, the transfer unit:

• Redirects power from the transaxle to the rear drivetrain
• Adjusts torque distribution via an electronically controlled coupling
• Continuously manages power balance between front and rear

When it overheats, the system protects itself by reducing rear engagement.

This kit directly addresses that heat buildup.

Key Features

Dedicated Pipe-Type Transfer Oil Cooler

Cools transfer oil independently without affecting engine coolant, engine oil, or intercooler performance.

High-Flow Electric Oil Pump

Actively circulates transfer oil through the cooling circuit under high-load conditions.

Dedicated Pump Controller

Includes AUTO, FULL AUTO, and MANUAL modes depending on vehicle compatibility.

Transfer Protection Cancel Function Support

For compatible vehicles, this system integrates with the 4WD mode select switch to allow full-time AWD during circuit driving.

(Important: This feature only applies to vehicles equipped with the appropriate program — see compatibility section below.)

Banjo-Type Oil Outlet Fitting

Impact-resistant design with PT1/8 port for easy oil service and optional temperature sensor mounting.

Compatibility & Model Year Notes

Part Number: 27002-AT001
Vehicle: 2023+ Toyota GR Corolla (GZEA14H)
Engine: G16E-GTS

Vehicles Manufactured:

• From September 2023 – does NOT support transfer protection cancel function
• From August 2024 (North America LHD) – supports cancel function
• From May 2025 (Japan & RHD) – supports cancel function

If your vehicle does not have the transfer protection cancellation program, do NOT connect the 4WD mode select switch connector — doing so may disable AWD.

Always confirm your production date before installation.

Operating Modes

The pump controller includes:

AUTO Mode
For vehicles without cancellation program

FULL AUTO Mode
For vehicles equipped with cancellation program

MANUAL Mode
For maintenance or controlled operation

The system monitors pump current and includes overcurrent protection safeguards.

Recommended Usage

This product is designed primarily for circuit and high-load performance use.

• Activate system before spirited driving
• Recommended oil temperature before activation: 60°C or higher
• Use stock-spec transfer oil (HKS recommends 75W-90 equivalent)
• Estimated installation time: approximately 8 hours

Some minor trimming of bumper ducts or undercovers may be required during installation.

Professional installation is strongly recommended.

Included Components

• Transfer cooler pipe
• Electric oil pump
• Pump controller
• Oil filter
• Mounting brackets
• Hose and wiring harness set

Who Should Buy This?

This kit is ideal for:

• GR Corolla owners doing track days
• High-speed endurance driving
• Aggressive canyon use
• AWD-focused builds
• Anyone wanting long-term drivetrain protection

If you drive your GR Corolla hard, especially in hot climates, this upgrade directly addresses one of the platform’s known heat management limitations.

Frequently Asked Questions

Does this increase horsepower?
No. This is a drivetrain protection and thermal management system, not a power mod.

Will this void my warranty?
Using the transfer protection cancellation function may impact warranty coverage. Always review your manufacturer warranty terms.

Is this necessary for daily driving?
For normal commuting, it is not required. It is designed for high-load and performance use.

Does it keep the car in AWD permanently?
Only on compatible vehicles equipped with the cancellation program, and when properly configured.

How difficult is installation?
Estimated installation time is approximately 8 hours. Professional installation is strongly recommended due to drivetrain and electrical integration.