ATF Power Steering Fluid Replacement Subaru STi/WRX:

This is a step by step guide in replacing the ATF power steering fluid on your Subaru STi/WRX. This is pretty much a two person job unless you have a suction gun. I like to use Mobil 1 ATF Synthetic fluid.

Mobil 1 Synthetic Automatic Transmission Formula

1.) Open hood and remove two 12 mm bolts on intake scoop. Remove the scoop (lift up right side and it will pop off).

2.) Remove cap from power steering reservoir.

3.) Raise the car up (use jack stands “Safety first”), not to high. A person must sit in the car while another person fills the power steering reservoir.

4.) Under the car – Remove the Plastic engine cover under the car, using the 12 mm socket (5 bolts) and flat tip screw driver (4 clips).

5.) Remove the center jack plate, using 14 mm socket (4 nuts), and 12mm socket and 12 mm wrench (2 rear bolts & 2 front nuts/bolts).

ATF Power Steering Fluid Replacement Subaru STi/WRX:

6.) Place a oil pan under the power steering gear box (just above jack plate location).

7.) Using the pliers slide one of the clips off the rubber hose (pipe joint) on the power steering gear box. Fluid will drain out immediately, so have that pan already in place under the hose.

8.) Slowly pour in some ATF into the reservoir, while another person sits in the car and SLOWLY turns the steering wheels from lock to lock – perform this at least 3 times. Watch the fluid in the reservoir so that it doesn’t drain out, and watch under the car to see when the old fluid is flushed out. The OEM fluid was brown and I used Mobile 1 ATF Synthetic which was red, so I could see when all the old fluid was flushed.

9.) Re-attach rubber hose (pipe joint) and slide the clip back into place. Put jack plate back on and put plastic undercover back on.

10.) Pour in ATF to the MAX cold line on the reservoir and be ready to add more when the person turns the steering wheel.

ATF Power Steering Fluid Replacement Subaru STi/WRX:

11.) Slowly turn the steering wheel lock to lock (3x or more) and watch the reservoir until bubbles stop appearing. Add ATF as needed! DO NOT LET THE RESERVOIR GET TOO LOW!!! This will suck more air into the system.

12.) Start the car and Slowly turn the steering wheel lock to lock (3x or more) and watch the reservoir until bubbles stop appearing. Add ATF as needed.

13.) Lower car onto the ground. Slowly turn the steering wheel lock to lock (3x or more) and watch the reservoir until bubbles stop appearing. Add ATF as needed.

14.) “In case the following happens, leave it about a half an hour and then do” STEP 11 to STEP 13 again:
a. Fluid level changes over 3 mm (0.12 in)
b. Bubbles remain on the upper surface of the fluid
c. Grinding noise is generated from power steering pump.

15.) Replace power steering cap and reinstall the intake scoop.

Now enjoy your smoother steering with your brand new ATF on your Subaru WRX/STi!

Tools needed:
Flat tip screw driver
10 mm socket
12 mm socket
14 mm socket
12 mm wrench
Pliers
Drain pan