🔧 Transmission Fluid - Drain and Refill

Your Sienna uses a sealed-style automatic transmission with a level check that depends on fluid temperature. The job is a drain and refill, not a full flush, and the final fluid level must be set with the vehicle level and the transmission at the correct temperature.

Difficulty Level: Intermediate | Estimated Time: 1.5-2.5 hours

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⚠️ Safety & Precautions

• Work on a level surface. The final fluid level must be checked with the vehicle level.
• Transmission fluid can be hot. Let the vehicle cool before opening drain or overflow plugs.
• Keep dirt out of the transmission. Clean the area around every plug before removing it.
• Do not overfill. Too much fluid can cause shifting problems and leaks.
• A scan tool that reads transmission fluid temperature is strongly recommended for the final level check.

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🔧 Required Tools

You'll need the following tools for this repair:

• Funnel with long hose
• Drain pan
• 3/8-inch drive ratchet
• Torque wrench
• 10mm socket
• 24mm socket
• Hex bit socket set
• Fluid transfer pump
• Scan tool with transmission fluid temperature display
• Floor jack
• Jack stands rated for vehicle weight
• Wheel chocks
• Safety glasses
• Nitrile gloves
• Shop towels

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Automatic transmission fluid, Toyota WS specification - Qty: 5 quarts
• Transmission drain plug gasket - Qty: 1
• Transmission overflow plug gasket - Qty: 1
• Transmission fill plug gasket - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and chock the rear wheels.
• Warm the vehicle slightly so the fluid drains better, but do not make it fully hot.
• Raise and support the vehicle level on jack stands. Keep it level front to rear and side to side.
• Have the scan tool ready to read transmission fluid temperature before you start the final level check.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Open the fill plug first

• Use a 24mm socket to loosen the transmission fill plug first. This confirms you can refill it before draining.
• Never drain it before checking the fill plug.

Step 2: Drain the old fluid

• Place a drain pan under the transmission.
• Use a hex bit socket to remove the drain plug and let the fluid drain completely.
• Remove the drain plug gasket and replace it with a new one.

Step 3: Reinstall the drain plug

• Install the drain plug by hand first.
• Use a torque wrench to tighten the drain plug to 39 Nm (29 ft-lbs).

Step 4: Refill with new fluid

• Use a fluid transfer pump and funnel with long hose to add Toyota WS fluid through the fill hole.
• Start with about 4 quarts, then refill in smaller amounts later during the level check.
• Install the fill plug loosely for now.

Step 5: Warm the transmission to check level

• Start the engine and keep the vehicle level.
• Use a scan tool with transmission fluid temperature display to monitor fluid temperature.
• Move the shifter slowly through each gear position, pausing briefly in each one, then return to Park.
• Let the transmission fluid reach the correct check range, typically approximately 40°C to 45°C (104°F to 113°F).

Step 6: Set the final fluid level

• With the engine idling and the vehicle level, remove the overflow/check plug using a hex bit socket.
• If no fluid drips out, add fluid through the fill hole with the fluid transfer pump until it begins to dribble from the overflow opening.
• If fluid flows out steadily, let it drain until it becomes a thin drip.

Step 7: Close the transmission

• Install the overflow/check plug with a new gasket.
• Torque the overflow/check plug to 29 Nm (21 ft-lbs).
• Torque the fill plug to 39 Nm (29 ft-lbs).

Step 8: Clean up and inspect

• Wipe the case clean with shop towels.
• Check for leaks around the drain, fill, and overflow plugs.
• Lower the vehicle and test drive gently.

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✅ After Repair

• Drive for 10-15 minutes and check for leaks again.
• Make sure shifts are smooth and there are no warning lights.
• If the fluid was badly burned, consider a second drain and refill after a short drive to refresh more of the old fluid.

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💰 DIY vs Shop Cost

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

DIY Cost: $60-$110 (parts only)

You Save: $120-$210 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-2.5 hours.

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🎯 Ready to get started?

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