🔧 Tundra - Transmission Fluid Drain & Refill

On your Tundra, the safest DIY service is a drain-and-refill (not a power flush). You’ll drain the old ATF, refill with the correct Toyota-spec fluid, then set the final fluid level using the overflow/check procedure at a specific fluid temperature.

Difficulty Level: Intermediate | Estimated Time: 1.5-3 hours

Assumption: Your Tundra uses Toyota WS fluid and a sealed overflow-style level check (common on this transmission).

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⚠️ Safety & Precautions

• 🛑 Support the truck safely: use jack stands on the frame; never rely on a jack.
• 🔥 ATF and exhaust parts can be hot; wear gloves and safety glasses.
• 📏 Fluid level is very sensitive to angle—keep the truck level front-to-rear and side-to-side when checking level.
• ⚙️ Engine will run during level-setting; keep hands/clothes away from the fan, belts, and driveshafts.

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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 (10-quart minimum)
• Shop rags
• Ratchet
• 3/8-inch drive torque wrench (10-80 ft-lb range)
• 5mm hex bit socket
• 24mm socket
• Fluid transfer pump (specialty)
• OBD2 scan tool with transmission fluid temp (specialty)
• Infrared thermometer
• Funnel

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Automatic transmission fluid (Toyota WS-compatible) - Qty: 8 quarts
• Transmission drain plug gasket/crush washer - Qty: 1
• Transmission fill plug gasket/crush washer - Qty: 1
• Transmission overflow/check plug gasket/crush washer - Qty: 1
• Brake cleaner - Qty: 1

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📋 Before You Begin

• 🧱 Park on a level surface, set the parking brake, and place wheel chocks behind the rear tires.
• 📏 Lift and support the truck so it sits level on jack stands (level is required for an accurate ATF level).
• 🧪 Confirm you can remove the fill plug before draining (this prevents getting stuck unable to refill).
• 🌡️ Plan your temperature check method: best is an OBD2 scan tool with ATF temp; backup is an infrared thermometer aimed at the transmission pan.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Access the transmission service plugs

• Use a floor jack (rated 3-ton minimum) and jack stands (rated 3-ton minimum) to support the truck level.
• Place a drain pan (10-quart minimum) under the transmission.
• Wipe the area clean with shop rags so dirt doesn’t fall into the transmission.

Step 2: Remove the fill plug first (important)

• Locate the transmission fill plug on the transmission case.
• Use a 24mm socket with a ratchet to loosen and remove the fill plug.
• If it won’t loosen, stop here (don’t drain yet). Spray with brake cleaner, wipe, and try again carefully.
• When reinstalling later: Torque to 39 Nm (29 ft-lb).

Step 3: Drain the old transmission fluid

• Locate the transmission drain plug at the bottom of the pan.
• Use a 24mm socket and ratchet to remove the drain plug and let fluid drain into the drain pan.
• Let it drip until it slows to an occasional drip (usually 10–20 minutes).
• Clean the drain plug, install a new drain plug gasket/crush washer, then reinstall the plug.
• Torque to 27 Nm (20 ft-lb).

Step 4: Add fresh ATF (initial fill)

• Insert the hose from a fluid transfer pump (specialty) into the fill hole (a transfer pump pushes fluid uphill into the transmission).
• Pump in Automatic transmission fluid (Toyota WS-compatible) until fluid starts to dribble back out of the fill hole.
• Reinstall the fill plug loosely by hand for now (you’ll remove it again during the level-setting step).

Step 5: Warm the fluid and cycle the shifter

• Connect an OBD2 scan tool with transmission fluid temp (specialty) and monitor ATF temperature.
• Start the engine and keep your foot firmly on the brake.
• Move the shifter slowly through each gear position (P-R-N-D and lower ranges), pausing ~3 seconds in each, then return to Park.
• Slow shifting helps fill all passages.

Step 6: Set the ATF level using the overflow/check plug

• Locate the overflow/check plug (this plug controls final fluid height; excess drains out when the fluid is at the correct temperature).
• With the engine running, use a 5mm hex bit socket with a ratchet to carefully remove the overflow/check plug.
• Bring ATF temperature to 40–45°C (104–113°F) using the scan tool reading. If you don’t have ATF temp on the scan tool, use an infrared thermometer aimed at the transmission pan and target the same temperature range (less precise).
• If no fluid comes out at 40–45°C, remove the fill plug with a 24mm socket, pump in more ATF with the fluid transfer pump (specialty) until a thin stream begins to come out of the overflow/check hole.
• If a heavy stream pours out, wait until it reduces to a thin stream/drip at 40–45°C.
• Install a new overflow/check plug gasket/crush washer and reinstall the overflow/check plug.
• Torque to 20 Nm (15 ft-lb).

Step 7: Final tighten and clean-up

• Remove the fill plug again with a 24mm socket (if you tightened it earlier).
• Install a new fill plug gasket/crush washer and reinstall the fill plug.
• Torque to 39 Nm (29 ft-lb).
• Spray any spilled ATF with brake cleaner and wipe clean with shop rags.

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✅ After Repair

• 🧪 With the truck still level, check for leaks around the drain, fill, and overflow/check plugs.
• 🚗 Test drive 10–15 minutes, then re-check underneath for seepage.
• 🛑 If you notice delayed engagement, slipping, or harsh shifting, stop driving and re-check level (incorrect level can cause symptoms).
• ♻️ Dispose of used ATF properly at a recycling center/auto parts store that accepts waste fluids.

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💰 DIY vs Shop Cost

Shop Cost: $250-$450 (parts + labor)

DIY Cost: $70-$140 (parts only)

You Save: $180-$310 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3 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.