🔧 IS - Automatic Transmission Fluid Drain & Refill

This is a drain-and-refill service (not a power flush). Your IS uses a sealed-style automatic transmission that must be filled and leveled using an overflow/level plug at a specific fluid temperature.

Assumption: 2016 IS AWD uses Toyota/Lexus ATF WS and a temperature-based overflow level check; exact plug torques can vary by transmission variant.

Difficulty Level: Intermediate | Estimated Time: 2-4 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a cool drivetrain to avoid burns from hot ATF and exhaust.
• ⚠️ Keep the car perfectly level on four jack stands before setting fluid level.
• ⚠️ Never get under a vehicle supported only by a floor jack.
• ⚠️ Engine will run during level check—keep hands, hair, and clothing away from belts/fans.
• ⚠️ No battery disconnect is 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) x4
• Wheel chocks
• Safety glasses
• Nitrile gloves
• Drain pan (10-quart minimum)
• Socket set 8mm-19mm
• Ratchet 3/8" drive
• Torque wrench 10-100 ft-lbs
• Hex bit socket set (Allen) 5mm-10mm
• Trim clip removal tool
• Funnel with long hose
• Fluid transfer pump (hand pump) (specialty)
• OBD2 scan tool with transmission fluid temperature display (specialty)
• Infrared thermometer
• Shop towels
• 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) - Qty: 4-6 quarts
• Drain plug crush washer - Qty: 1
• Fill plug crush washer - Qty: 1
• Overflow/level plug crush washer - Qty: 1
• Transmission pan gasket - Qty: 1 (only if pan is removed)

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📋 Before You Begin

• Park on a level surface, set the parking brake, and place wheel chocks behind the rear wheels.
• Raise the car and support it on four jack stands so it sits level front-to-rear and side-to-side.
• Remove the front underbody splash shield(s) using a trim clip removal tool and 10mm socket.
• Set up your OBD2 scan tool to display transmission/ATF temperature. (This is the only reliable way to level the fluid.)
• Tip: Always loosen the fill plug first.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Locate the fill, drain, and overflow (level) plugs

• With the splash shield off, locate the transmission pan area.
• The fill plug is on the transmission case (used to pump new fluid in).
• The drain plug is at the lowest point of the pan/case.
• The overflow/level plug is a smaller plug that sets final fluid level (it acts like a “standpipe” inside).
• Use a shop light and brake cleaner spray to clean around plugs so dirt can’t fall in.

Step 2: Loosen the fill plug first

• Place the drain pan underneath.
• Use the correct hex bit socket (commonly 10mm) with a ratchet to loosen the fill plug.
• If the fill plug will not loosen, stop here—do not drain the transmission if you can’t refill it.
• When reinstalling later, use a torque wrench and Torque to factory spec.

Step 3: Drain the old ATF

• Use the correct hex bit socket with a ratchet to remove the drain plug.
• Let the ATF drain completely into the drain pan.
• Remove and discard the old crush washer (a soft sealing ring that prevents leaks).
• Clean the drain plug and threads using shop towels.

Step 4: Reinstall the drain plug with a new crush washer

• Install a new drain plug crush washer on the drain plug.
• Thread the drain plug in by hand first to avoid cross-threading.
• Tighten with a torque wrench: Torque to factory spec.

Step 5: Pump in fresh ATF WS through the fill hole

• Insert the hose from the fluid transfer pump into the fill hole.
• Pump in ATF WS until fluid begins to dribble back out of the fill hole.
• Install a new fill plug crush washer on the fill plug.
• Reinstall the fill plug finger-tight for now (final tightening after level set).

Step 6: Set the fluid level using the overflow/level plug (temperature-based)

• Start the engine and keep the car level on jack stands.
• With your foot on the brake, move the shifter slowly through P-R-N-D and back to P, pausing 2-3 seconds in each position.
• Watch ATF temperature on the OBD2 scan tool.
• When ATF is in the correct level-check range, remove the overflow/level plug using the correct hex bit socket and a ratchet.
• Correct result: a thin stream/dribble comes out, then slows to a drip.
• If nothing comes out, pump more ATF in through the fill hole using the fluid transfer pump until it dribbles from the overflow.
• If a heavy stream pours out, wait until it reduces to a drip (still at the correct temperature window).
• Reinstall the overflow/level plug with a new overflow/level plug crush washer and tighten with a torque wrench: Torque to factory spec.
• Tip: Temperature matters more than “how much you poured in.”

Step 7: Final-tighten the fill plug and reinstall the splash shield

• Remove the fill plug (if needed) to install the new crush washer (if not already installed), then reinstall.
• Tighten the fill plug using a torque wrench: Torque to factory spec.
• Clean any spilled ATF using brake cleaner spray and shop towels.
• Reinstall the underbody splash shield(s) using a 10mm socket and trim clip removal tool.

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✅ After Repair

• Start the engine and check underneath for leaks around the drain, fill, and overflow plugs.
• Take a 10-15 minute test drive, then recheck for seepage once parked.
• If you notice delayed engagement, slipping, or new whining noises, stop driving and re-check the level using the same temperature-based overflow method.
• Tip: Keep your drained fluid to compare color/amount.

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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.