🔧 Impreza - Manual Transmission Fluid Change

On your Impreza with a manual gearbox, the transmission fluid (gear oil) lubricates the gears, bearings, and synchronizers so shifting stays smooth and parts don’t wear out early. The job is a simple drain-and-refill, but it’s important to open the fill plug first and keep the car perfectly level for an accurate fluid level.

Difficulty Level: Intermediate | Estimated Time: 1-2 hours

---

⚠️ Safety & Precautions

• 🛑 Support the car with jack stands on a solid, level surface; never rely on a jack alone.
• 🔥 Warm fluid drains better, but the exhaust and fluid can be hot—wear gloves and safety glasses.
• 📏 Keep the car level front-to-back and side-to-side when refilling, or the fluid level will be wrong.
• 🔩 Always loosen the fill plug before draining; if the fill plug is stuck and you already drained it, you’re stranded.

---

🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 2-ton minimum)
• Jack stands (rated 2-ton minimum)
• Wheel chocks
• Safety glasses
• Nitrile gloves
• Drain pan (at least 8-quart)
• 21mm socket
• 3/8" drive ratchet
• 6" socket extension
• Torque wrench (10-100 ft-lb range)
• Trim clip remover
• Funnel with hose
• Fluid transfer pump (specialty)
• Shop rags

---

🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Manual transmission gear oil (SAE 75W-90, GL-5) - Qty: 4 quarts
• Transmission drain plug crush washer - Qty: 1
• Transmission fill plug crush washer - Qty: 1

---

📋 Before You Begin

• 🚗 Drive 5–10 minutes to warm the fluid, then park on a level surface.
• 🧱 Set the parking brake, put the shifter in 1st gear, and place wheel chocks behind the rear wheels.
• ⬆️ Jack up the front with a floor jack and support with jack stands at the proper lift points; keep the car as level as possible.
• 🧼 Lay out shop rags and a drain pan; gear oil has a strong smell and can be messy.
• Fluid transfer pump = hand pump to push fluid up.

---

🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the front under cover (if equipped)

• Use a trim clip remover to pop out the plastic clips.
• Use a 21mm socket only if your cover uses bolts (some do); set all hardware aside.

Step 2: Locate the fill and drain plugs

• From under the front, find the transmission case.
• The drain plug is on the bottom of the transmission case.
• The fill plug is on the side of the transmission case (higher up than the drain).
• Clean around both plugs with shop rags so dirt can’t fall inside.

Step 3: Loosen the fill plug first

• Place the drain pan under the area (a little fluid may seep).
• Use a 21mm socket, 6" extension, and 3/8" drive ratchet to loosen the fill plug.
• Once it breaks loose, leave it threaded in by hand for now.
• If it won’t loosen, stop here.

Step 4: Drain the old fluid

• Move the drain pan directly under the drain plug.
• Use a 21mm socket, extension, and ratchet to remove the drain plug.
• Let it drain until it slows to an occasional drip (usually 10–15 minutes).
• Wipe the drain plug clean with shop rags (many have a magnet that collects metal fuzz).
• Install a new drain plug crush washer on the drain plug.

Step 5: Reinstall and torque the drain plug

• Thread the drain plug in by hand first to avoid cross-threading.
• Use a torque wrench and 21mm socket to tighten: Torque to 50 N·m (37 ft-lb).

Step 6: Fill with new gear oil

• Remove the fill plug fully using the 21mm socket, extension, and ratchet.
• Install a new fill plug crush washer on the fill plug (set the plug aside clean).
• Insert the hose from a fluid transfer pump (specialty) or funnel with hose into the fill hole.
• Add SAE 75W-90 GL-5 gear oil until it begins to slowly seep back out of the fill hole (that’s the correct level when the car is level).
• Fill slowly at the end to avoid overfill.

Step 7: Reinstall and torque the fill plug

• Thread the fill plug in by hand.
• Use a torque wrench and 21mm socket to tighten: Torque to 50 N·m (37 ft-lb).
• Wipe the area clean with shop rags so leaks are easy to spot.

Step 8: Reinstall the under cover and lower the car

• Reinstall the under cover using the trim clip remover to seat the clips.
• Use the floor jack to lift slightly, remove the jack stands, then lower the car.

---

✅ After Repair

• 🧪 Start the engine and, with the clutch pressed, shift through all gears while parked (don’t drive yet) to circulate oil.
• 🚗 Take a short 5–10 minute test drive and confirm shifting feels normal.
• 🔍 Park on clean pavement and check underneath for any seepage around the fill/drain plugs.
• 🧴 Dispose of used gear oil at a recycling center or parts store that accepts fluids.

---

💰 DIY vs Shop Cost

Shop Cost: $180-$320 (parts + labor)

DIY Cost: $45-$90 (parts only)

You Save: $135-$230 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 hours.

---

🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.