🔧 RX - Automatic Transmission Fluid Drain & Fill (WS)

This service is a “drain and fill,” not a full flush. You’ll drain what’s in the pan, then refill and set the fluid level at a specific transmission temperature using the overflow level method.

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

Assumption: your RX uses Toyota/Lexus WS fluid and an overflow-type level check (typical for this model).

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⚠️ Safety & Precautions

• ⚠️ Work on a level surface and support the RX with jack stands before going underneath.
• ⚠️ Transmission fluid can be hot. Let the RX cool if you just drove it.
• ⚠️ The level is temperature-sensitive. Setting level at the wrong temp can cause shifting issues.
• ⚠️ Keep the engine running only when instructed and keep hands/tools clear of belts and fans.

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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 (8-quart minimum)
• Torque wrench (10–100 ft-lbs range)
• Socket set (8mm–19mm)
• Ratchet
• Trim clip removal tool
• Fluid transfer pump
• OBD2 scan tool with ATF temperature data (specialty)
• Infrared thermometer (optional)
• Hex bit socket set (5mm–10mm)
• 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 WS-spec) - Qty: 4-6 quarts
• Transmission drain plug gasket (crush washer) - Qty: 1
• Transmission fill plug gasket (crush washer) - Qty: 1
• Transmission overflow/level plug gasket (if equipped) - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and place wheel chocks behind the rear tires.
• Lift the front and support with jack stands. The RX must sit level for accurate fluid level checking.
• Locate your fill plug before draining. Tip: never drain if you can’t refill.
• Connect your OBD2 scan tool with ATF temperature data (specialty). This tool reads transmission fluid temperature from the vehicle computer.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the underbody cover (if equipped)

• Use a trim clip removal tool to pop out plastic clips.
• Use an 8mm socket (or applicable size) with a ratchet to remove bolts/screws.
• Set the panel and hardware aside in a safe spot.

Step 2: Confirm you can loosen the fill plug

• Place the drain pan underneath the transmission.
• Use the correct socket or hex bit socket with a ratchet to carefully crack the fill plug loose.
• If it won’t loosen, stop here—do not drain yet.

Step 3: Drain the old transmission fluid

• Use the correct socket (or hex bit socket) and ratchet to remove the drain plug.
• Let fluid drain until it slows to a drip.
• Clean the drain plug and sealing surface using shop rags and brake cleaner spray.
• Replace the drain plug gasket with a new crush washer.

Step 4: Reinstall the drain plug

• Thread the drain plug in by hand to avoid cross-threading.
• Use a torque wrench to tighten: Torque to 49 Nm (36 ft-lbs).

Step 5: Refill with WS-spec transmission fluid

• Remove the fill plug fully using the correct socket or hex bit socket and ratchet.
• Install your fluid transfer pump into the fluid bottle and pump fluid into the fill port.
• Add roughly what you drained (most drain-and-fills are about 3–5 quarts).
• Reinstall the fill plug loosely for now (finger tight) to prevent drips while you prep to level-set.

Step 6: Set the transmission fluid level (overflow method)

• Start the engine and keep the RX on jack stands, level and secure.
• With your foot on the brake, slowly move the shifter through P-R-N-D and back to P, pausing 2–3 seconds in each gear.
• Use your OBD2 scan tool with ATF temperature data (specialty) to monitor ATF temperature.
• When ATF temperature reaches 40–45°C (104–113°F), remove the overflow/level check plug using the correct hex bit socket and ratchet.
• Interpret what you see:
  • If fluid comes out in a steady stream, let it drain until it becomes a thin drip.
  • If little/no fluid comes out, add fluid through the fill port using the fluid transfer pump until it begins to overflow, then let it settle to a thin drip.
• Install a new gasket on the overflow/level plug (if used) and tighten with a torque wrench: Torque to 20 Nm (15 ft-lbs).
• Turn the engine off.

Step 7: Final tighten the fill plug and reinstall the cover

• Remove the fill plug again briefly (if needed) to replace its gasket/crush washer.
• Install the fill plug and tighten with a torque wrench: Torque to 39 Nm (29 ft-lbs).
• Reinstall the underbody cover using the trim clip removal tool and 8mm socket with a ratchet.
• Lower the RX safely using the floor jack.

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✅ After Repair

• Wipe down any spilled fluid using shop rags and brake cleaner spray.
• Start the RX and check underneath for leaks around the drain/fill/overflow plugs.
• Test drive 10–15 minutes. Verify smooth shifts and no slipping or flare.
• Recheck for leaks after the test drive.
• Tip: save your drain amount for next time.

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💰 DIY vs Shop Cost

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

DIY Cost: $60-$140 (parts only)

You Save: $110-$390 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?

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.