DIY 2019 Lexus RX350 Transmission Service

Introduction

This tutorial guides you through the process of performing a transmission service on a 2019 Lexus RX350. The vehicle features a sealed 8-speed transmission that requires careful handling to ensure proper fluid levels without the use of a traditional dipstick. You will learn how to safely drain and refill the transmission fluid, verify the correct temperature for accurate fluid levels, and understand essential maintenance tips.

Step 1: Gather Required Tools and Supplies

Before starting the transmission service, make sure you have the following tools and supplies on hand:

• Fluid Type: Toyota ATF WS (do not use older T-IV or generic fluids)
• Service Capacity: Approximately 2.5–3.2 quarts for a standard drain and fill
• Tools:
  • 24mm socket (for the Fill plug)
  • 10mm Allen/Hex socket (for the Drain plug)
  • 6mm Allen/Hex socket (for the Overflow plug)
  • Fluid transfer pump
• Safety Gear: Gloves and safety glasses

Step 2: Identify the Transmission Plugs

Locate the three crucial plugs on your transmission:

• Fill Plug: Located on the side
• Drain Plug: Located on the bottom
• Overflow/Check Plug: Located at the bottom center

Understanding the location of these plugs is essential for a successful fluid exchange.

Step 3: Drain the Old Transmission Fluid

1. Prepare the Vehicle: Ensure the vehicle is on a flat surface and safely elevated if necessary.
2. Remove the Drain Plug: Use a 10mm Allen/Hex socket to carefully remove the drain plug. Allow the old fluid to completely drain into a suitable container.
3. Inspect the Fluid: Check the condition of the old fluid for any signs of metal shavings or discoloration, which may indicate issues.

Step 4: Fill the Transmission with New Fluid

1. Replace the Drain Plug: Once all the old fluid is drained, reinstall and tighten the drain plug securely.
2. Use the Fluid Transfer Pump: Insert the pump into the Fill plug and begin adding the new Toyota ATF WS fluid.
3. Fill to Approximate Capacity: Aim for approximately 2.5–3.2 quarts, leaving room for the overflow adjustment.

Step 5: Verify and Adjust Fluid Level

1. Overfill Slightly: Add about 0.5 quarts more than the estimated capacity.
2. Start the Engine: Let the engine idle until the transmission fluid reaches a temperature between 104°F and 113°F. You can check the temperature using one of two methods:
   • Paperclip Jump Method: Use a paperclip to jump the OBD2 connector to read the temperature.
   • OBD2 Scanner: Connect an OBD2 scanner to monitor transmission fluid temperature.
3. Open the Overflow Plug: Once at the correct temperature, carefully open the overflow plug.
4. Drain Excess Fluid: Allow the excess fluid to drain until it becomes a thin trickle. This ensures the correct fluid level.
5. Seal the Overflow Plug: Once the excess fluid has drained, replace the overflow plug securely.

Step 6: Optional Filter Replacement

If you choose to replace the internal metal/felt filter, you will need to drop the transmission pan. This process involves:

• Removing bolts securing the pan
• Carefully lowering the pan to access the filter
• Replacing the old filter with a new one before reattaching the pan

Conclusion

Performing a transmission service on a 2019 Lexus RX350 requires careful attention to detail, especially regarding fluid levels and temperature. By following these steps, you can successfully drain and refill the transmission fluid, ensuring optimal performance. Always remember to use the correct fluid type and monitor the temperature closely. For ongoing maintenance, consider consulting a professional mechanic if you're unsure about any steps. Happy DIYing!