🔧 Forester - Automatic Transmission Fluid Drain & Refill

This job replaces a portion of your automatic transmission fluid (ATF) by draining the pan and refilling through the dipstick tube. It’s the safest DIY method for your Forester because it avoids high-pressure flushing and still refreshes the fluid.

Difficulty Level: Intermediate | Estimated Time: 1.0-2.0 hours

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⚠️ Safety & Precautions

• 🛑 Work on a level surface and support the vehicle with jack stands—never rely on a jack alone.
• 🔥 ATF can be hot; let the transmission cool if you just drove.
• 🧯 Keep ATF off the exhaust and clean spills immediately (smoke/fire risk).
• 🧤 Wear gloves and safety glasses—ATF is slippery and irritating to skin/eyes.

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🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• Safety glasses
• Nitrile gloves
• Drain pan (at least 10-quart)
• 17mm socket
• 3/8" drive ratchet
• Torque wrench (10–100 ft-lbs range)
• 12mm socket
• Flat trim clip tool
• Long-neck funnel
• Measuring container (quart/liter marked)
• Shop rags
• Infrared thermometer (specialty)

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Automatic transmission fluid (Subaru ATF-HP) - Qty: 5 quarts
• Transmission drain plug crush washer - Qty: 1

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📋 Before You Begin

• 🧭 Park on level ground, set the parking brake, and chock the rear wheels.
• 📏 Plan to measure what you drain and refill the same amount (this keeps the level close before final checking).
• 🌡️ If the vehicle was driven, wait until the transmission pan is warm—not scorching—before draining.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Warm the fluid slightly

• Start the engine and let it idle 3–5 minutes, then shut it off.
• Warm fluid drains faster and more completely.

Step 2: Safely raise and level the vehicle

• Use a floor jack (rated 3-ton minimum) to lift the front, then support with jack stands (rated 3-ton minimum).
• Use wheel chocks to prevent rolling.
• Make sure the vehicle is as level as possible for an accurate level check later.

Step 3: Remove the lower cover (if equipped)

• Use a 12mm socket and 3/8" drive ratchet to remove the bolts.
• Use a flat trim clip tool to pop out any plastic clips without breaking them.

Step 4: Drain the transmission fluid

• Place the drain pan (at least 10-quart) under the transmission drain plug.
• Use a 17mm socket with a 3/8" drive ratchet to loosen and remove the drain plug.
• Let the fluid drain completely (usually 10–20 minutes).
• Pour the drained ATF into a measuring container (quart/liter marked) so you know how much to refill.

Step 5: Reinstall the drain plug with a new crush washer

• Wipe the drain plug area clean using shop rags.
• Install a new transmission drain plug crush washer (a soft metal sealing ring that prevents leaks).
• Thread the plug in by hand first to avoid cross-threading.
• Use a torque wrench (10–100 ft-lbs range) with a 17mm socket and Torque to 44 Nm (32 ft-lbs).

Step 6: Refill through the dipstick tube

• Open the hood and locate the transmission dipstick.
• Insert a long-neck funnel into the dipstick tube.
• Add the same amount you measured coming out, using automatic transmission fluid (Subaru ATF-HP).
• Add slowly to avoid overfilling.

Step 7: Circulate fluid and set the level

• Start the engine and let it idle.
• With your foot on the brake, move the shifter slowly through each gear position, pausing ~2 seconds in each, then return to Park.
• Use an infrared thermometer (specialty) to check transmission pan temperature and aim for a fully-warmed check (roughly 70–80°C / 158–176°F).
• With engine idling and vehicle level, pull the dipstick, wipe it with shop rags, reinsert fully, then pull again and read the level.
• If low, add ATF in small amounts (about 0.25 quart at a time) through the funnel, then recheck.

Step 8: Reinstall the lower cover and clean up

• Reinstall the cover using a 12mm socket and 3/8" drive ratchet.
• Wipe any spilled ATF off with shop rags.

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✅ After Repair

• 🧪 Test drive 10–15 minutes, then recheck the dipstick level on level ground with the engine idling.
• 🔍 Look underneath for any seepage at the drain plug area.
• 🧴 Dispose of used ATF at a recycling center/parts store—don’t pour it out.

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💰 DIY vs Shop Cost

Shop Cost: $220-$380 (parts + labor)

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

You Save: $130-$330 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.

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🎯 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.