This procedure covers draining and refilling the automatic transmission fluid on a 2015-2020 Ford F-150 with 3.5L EcoBoost engine, including filter replacement if accessible.

Warnings

Tools required

Parts

• Transmission drain plug crush washer × 1 — Use OEM specification
• Transmission fluid pan gasket × 1 — Only if pan is removed

Fluids

• Motorcraft MERCON LV ATF — 11 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine and transmission to cool for minimum 1 hour if recently driven
3. Gather all required fluids, tools, and parts before beginning
4. Raise vehicle and secure on jack stands at all four corners to ensure level working surface
5. Remove engine splash shield if equipped to access transmission pan

Procedure

1. 1

   Locate transmission drain plug
   Position drain pan under transmission pan. Locate the drain plug on the passenger side of the transmission pan, near the rear. Clean area around drain plug to prevent contamination.
2. 2

   Drain transmission fluid
   Using appropriate socket, slowly loosen drain plug. Allow plug to spin out by hand for last few threads to control fluid flow. Remove drain plug completely and allow fluid to drain fully into pan. This will take 5-10 minutes. Inspect drained fluid for metal particles or burning smell which may indicate transmission damage.
   ⚠Fluid may still be warm. Wear protective gloves and eye protection.
3. 3

   Inspect and replace drain plug washer
   Remove old crush washer from drain plug and discard. Clean drain plug threads with clean shop towel. Install new crush washer onto drain plug. Ensure washer seats properly against plug shoulder.
4. 4

   Reinstall drain plug
   Thread drain plug into transmission pan by hand to avoid cross-threading. Once seated, torque drain plug to specification using torque wrench.
   Torque spec

   Oil Drain Plug35 Nm (26 lb-ft)
5. 5

   Locate transmission fill plug
   Locate the fill/check plug on the driver side of the transmission case, approximately mid-height. This plug serves as both fill point and overflow. Clean area around fill plug thoroughly.
6. 6

   Remove fill plug
   Using appropriate socket, remove fill/check plug. A small amount of residual fluid may drain out. This is normal.
7. 7

   Fill transmission with new fluid
   Using fluid transfer pump and flexible hose, pump approximately 5-6 quarts of new Motorcraft MERCON LV ATF into fill hole. Fill slowly to allow fluid to settle and air to escape. Stop when fluid begins to drip from fill hole opening.
   ℹ️Initial fill amount will be less than total capacity as fluid remains in torque converter and valve body.
8. 8

   Reinstall fill plug temporarily
   Thread fill plug back into transmission case hand-tight only. Do not torque at this time as fluid level check will require plug removal again.
9. 9

   Lower vehicle and start engine
   Lower vehicle to ground. Start engine and allow to idle. With foot on brake, shift through all gear positions (P-R-N-D and back to P), pausing 3 seconds in each position. This circulates fluid through transmission.
10. 10

    Check fluid temperature and level
    With engine idling in Park, monitor transmission fluid temperature using scan tool or infrared thermometer pointed at transmission case. Target temperature is 150-170°F (65-77°C). Once at temperature, raise vehicle back onto jack stands. Remove fill plug. Fluid should drip steadily from fill hole. If no fluid drips, add fluid until it begins to overflow. If fluid pours out rapidly, too much fluid is present - allow excess to drain until steady drip is achieved.
    ⚠Fluid will be hot at operating temperature. Position drain pan and use caution when removing fill plug.
11. 11

    Final fill plug installation
    With engine still running and fluid at correct temperature dripping from fill hole, install fill plug and torque to specification. Use same torque value as drain plug.
    Torque spec

    Oil Drain Plug35 Nm (26 lb-ft)
12. 12

    Shut down and reinstall shields
    Turn off engine. Reinstall engine splash shield if removed. Lower vehicle to ground. Dispose of used transmission fluid properly at recycling facility.

Reassembly

1. Ensure both drain plug and fill plug are torqued to specification with new crush washers
2. Verify no fluid leaks are present around drain or fill plugs before moving vehicle
3. Reset transmission adaptive learning if desired using appropriate scan tool (optional)

Verification

• Start engine and verify no fluid leaks from drain or fill plugs
• Take vehicle for 5-10 minute test drive, cycling through all gears
• Verify smooth shifting with no slipping, flaring, or harsh engagements
• After test drive, check for leaks again with vehicle at operating temperature
• Monitor transmission behavior over next few days as adaptive learning resets to new fluid characteristics

More procedures for this vehicle