🔧 QX50 - Transmission Fluid Drain & Refill

On your QX50, the safest DIY “transmission fluid change” is a drain-and-refill. It replaces a large portion of the old fluid and helps restore shift quality without the risks that can come with power-flushing an older transmission.

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

Assumption: Your QX50 uses the Nissan/INFINITI 7-speed automatic that takes Nissan Matic S fluid and has a dipstick tube for filling/level check.

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⚠️ Safety & Precautions

• ⚠️ Support the vehicle with jack stands on a level surface; never rely on a jack.
• ⚠️ Transmission fluid can be hot. Let the car cool enough to avoid burns.
• ⚠️ Keep the vehicle level while filling/checking level, or the reading will be wrong.
• ⚠️ Engine must be running for the final level check—keep hands/tools clear of moving parts.
• ⚠️ Battery disconnect is not 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 (at least 10-quart)
• Socket set (metric)
• 10mm socket
• Ratchet
• Torque wrench (10-80 Nm range)
• 19mm socket
• Trim clip removal tool
• Long-neck funnel
• Measuring container (marked in quarts)
• OBD2 scan tool with transmission fluid temperature (specialty)
• Infrared thermometer
• Shop towels

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Automatic transmission fluid (Nissan/INFINITI Matic S equivalent) - Qty: 5 quarts
• Transmission drain plug crush washer - 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 wheels.
• Warm the transmission slightly with a 10-minute drive so the fluid drains well, then shut the engine off.
• Gather a measuring container so you can refill the same amount you drain (simple and beginner-friendly).
• Plan your level-check method:
  • Preferred: Use an OBD2 scan tool that shows transmission fluid temperature.
  • Backup: Use an infrared thermometer aimed at the transmission pan (less accurate).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Lift and secure the vehicle

• Use a floor jack to lift the front, then place the vehicle on jack stands at the proper lift points.
• Use wheel chocks to prevent rolling.
• Confirm the vehicle sits level (important for refilling and level checking).

Step 2: Remove the lower cover (if equipped)

• Use a 10mm socket and ratchet to remove bolts.
• Use a trim clip removal tool to pop any plastic clips without breaking them.
• Set the cover and hardware aside in a neat pile.

Step 3: Locate the transmission drain plug

• Position a drain pan under the transmission pan area.
• Wipe around the drain plug with shop towels so dirt doesn’t fall in.

Step 4: Drain the old fluid

• Use a 19mm socket and ratchet to loosen the drain plug.
• Finish removing the plug by hand and let fluid drain into the drain pan.
• Pour the drained fluid into a measuring container and record the amount (this is your refill target).
• Tip: Expect roughly 3.5-5 quarts.

Step 5: Reinstall the drain plug with a new washer

• Remove the old washer and install the new drain plug crush washer.
• Thread the drain plug in by hand first (prevents cross-threading).
• Use a torque wrench to tighten the drain plug: Torque to 34 Nm (25 ft-lbs).

Step 6: Refill through the dipstick tube

• Open the hood and locate the transmission dipstick area.
• Insert a long-neck funnel into the dipstick tube.
• Pour in Nissan/INFINITI Matic S equivalent fluid equal to what you measured drained out.
• Go slowly and avoid overfilling.

Step 7: Circulate fluid and set the level (temperature matters)

• Start the engine and keep your foot on the brake.
• Slowly move the shifter through P-R-N-D and back to P, pausing ~3 seconds in each position.
• Connect an OBD2 scan tool with transmission fluid temperature (it reads the ATF temp from the car).
• When fluid is warm (typically around 35-45°C (95-113°F)), check the dipstick level with shop towels to wipe/insert/recheck.
• If you don’t have ATF temp on the scan tool, use an infrared thermometer on the transmission pan and aim for a similar temperature range.
• Add fluid in small amounts (about 0.25 quart at a time) using the funnel until it reads correctly.
• Tip: Overfilling can cause foaming and shifting issues.

Step 8: Reinstall the lower cover and lower the vehicle

• Reinstall the cover using the 10mm socket and ratchet.
• Lower the vehicle safely using the floor jack.

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✅ After Repair

• With the engine running, look underneath for leaks around the drain plug.
• Road test 10-15 minutes and confirm normal shifting (no slipping, flares, or harsh engagement).
• Park on level ground and recheck the dipstick level at operating temperature; top off if needed.
• Dispose of old ATF at a recycling center or parts store that accepts used fluids.

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💰 DIY vs Shop Cost

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

DIY Cost: $45-$95 (parts only)

You Save: $155-$405 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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