🔧 RX350 - Transmission Fluid Change

Your RX350 uses a “sealed” automatic transmission that’s serviced by draining and refilling, then setting the fluid level at a specific fluid temperature through the overflow/level tube. Doing the level-check step correctly is the key—overfill or underfill can cause shifting issues.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

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⚠️ Safety & Precautions

• 🛑 Support the SUV with jack stands on a level surface; never rely on a jack.
• 🔥 Transmission fluid can be hot—let it cool enough to work safely.
• ⚠️ The fluid level is set with the engine running on many Toyota/Lexus units—keep hands/clothes clear of moving parts.
• 🔌 No battery disconnect is typically required for this service.

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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)
• Socket set (8mm-19mm)
• Ratchet (3/8" drive)
• Torque wrench (10-80 ft-lbs range)
• Trim clip remover
• Fluid transfer pump (specialty)
• OBD2 scan tool that reads transmission fluid temperature (specialty)
• Funnel with hose
• Shop rags
• Brake cleaner spray

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Automatic transmission fluid (Toyota/Lexus ATF WS equivalent) - Qty: 4-8 quarts
• Transmission drain plug gasket/crush washer - Qty: 1
• Transmission fill plug gasket/crush washer - Qty: 1
• Overflow/level plug gasket - Qty: 1
• Transmission pan gasket - Qty: 1 (only if removing the pan)
• Transmission filter/strainer - Qty: 1 (only if removing the pan)

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📋 Before You Begin

• Park on a level surface, set the parking brake, and chock the rear wheels.
• Raise the front (and rear if needed) and keep the SUV level on jack stands.
• Plan to monitor transmission fluid temperature with your OBD2 scan tool that reads transmission fluid temperature (specialty) (this lets you set the level correctly).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Answer 2 quick questions (so I give the exact OEM torque specs + exact level-check temperature window)

• Is your RX350 FWD or AWD?
• Do you want a drain-and-fill (recommended DIY) or a pan drop + filter service?

Step 2: Remove the lower covers (underbody splash shields)

• Use a trim clip remover for plastic clips and a socket set (8mm-19mm) with a ratchet (3/8" drive) for bolts.
• Set hardware aside in a tray so nothing gets lost.

Step 3: Locate the fill plug first (important)

• Before draining anything, identify the transmission fill plug.
• Use your socket set (8mm-19mm) and ratchet (3/8" drive) to make sure the fill plug can be loosened.
• Never drain first if fill plug is stuck.

Step 4: Drain the old fluid

• Position a drain pan (10-quart minimum) under the transmission.
• Use the correct size from your socket set (8mm-19mm) with a ratchet (3/8" drive) to remove the drain plug.
• Let it drain until it slows to a drip, then reinstall the drain plug with a new gasket.
• Torque to OEM specification (I’ll provide the exact ft-lbs/Nm after your 2 answers in Step 1)

Step 5: Refill with ATF WS through the fill port

• Use a fluid transfer pump (specialty) to pump automatic transmission fluid (Toyota/Lexus ATF WS equivalent) into the fill port.
• Start by adding approximately what drained out (measure it using the markings on your drain pan if available).
• Reinstall the fill plug loosely for now.

Step 6: Set the fluid level using ATF temperature (the “sealed” level check)

• Connect your OBD2 scan tool that reads transmission fluid temperature (specialty) and display the transmission fluid temperature PID.
• With the vehicle level on jack stands, start the engine, then slowly move the shifter through each gear position and back to Park.
• Remove the overflow/level plug at the specified temperature window, then add/remove fluid until it becomes a thin steady drip.
• Torque to OEM specification (I’ll provide the exact overflow/fill torque + exact temp window after your 2 answers in Step 1)

Step 7: Reinstall covers and clean up

• Use brake cleaner spray and shop rags to clean any spilled ATF.
• Reinstall splash shields using the trim clip remover and socket set (8mm-19mm).

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✅ After Repair

• Test drive 10-15 minutes and confirm smooth shifting.
• Check for leaks around the drain, fill, and overflow/level plugs.
• Recheck for any drips on the splash shield area after the drive.

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💰 DIY vs Shop Cost

Shop Cost: $250-$550 (parts + labor)

DIY Cost: $60-$160 (parts only)

You Save: $190-$390 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3.0 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.