Transmission Fluid Change

This procedure drains and refills the transmission fluid on a 2015-2020 Ford F-150 with the 10R80 10-speed automatic transmission paired with the 3.5L EcoBoost engine.

Warnings

Tools required

Parts

• Transmission drain plug crush washer × 1 — BC3Z-7P197-A or equivalent

Fluids

• Motorcraft MERCON LV ATF — 6 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow engine and transmission to cool to safe working temperature
3. Raise front of vehicle with floor jack and support securely on jack stands
4. Locate transmission drain plug on bottom of transmission pan (passenger side, near rear)
5. Position drain pan directly beneath drain plug

Procedure

1. 1

   Drain transmission fluid
   Using appropriate socket (typically 8mm hex or square drive), slowly loosen the transmission drain plug. Allow fluid to drain completely into drain pan. This will take 5-10 minutes for fluid to fully drain. Inspect drained fluid for metal particles or burnt smell, which may indicate transmission problems.
2. 2

   Remove and inspect drain plug
   Once fluid flow stops, remove drain plug completely. Inspect drain plug threads for damage. Remove old crush washer from drain plug and discard. Wipe drain plug clean with shop towel.
3. 3

   Clean drain plug area
   Use wire brush and shop towel to clean the drain plug hole sealing surface on the transmission pan. Ensure no debris or old gasket material remains around the sealing surface.
4. 4

   Install drain plug with new crush washer
   Install new crush washer onto drain plug. Thread drain plug into transmission pan by hand until seated, then torque to specification using torque wrench. Do not over-tighten as this can strip aluminum pan threads.
   Torque spec

   Transmission Drain Plug30 Nm (22 lb-ft)
5. 5

   Lower vehicle
   Remove jack stands and carefully lower vehicle to ground. Ensure vehicle is on level surface for accurate fluid filling.
6. 6

   Locate transmission fill tube
   Open hood and locate transmission dipstick tube on passenger side of engine bay, near firewall. The 10R80 transmission uses the dipstick tube as the fill point.
7. 7

   Add transmission fluid
   Remove transmission dipstick. Insert long-neck funnel into dipstick tube. Add 5 quarts of Motorcraft MERCON LV ATF slowly, allowing fluid to drain down tube between additions. This initial fill accounts for what was drained.
8. 8

   Start engine and cycle transmission
   With parking brake engaged and foot on brake pedal, start engine. Allow to idle for 2-3 minutes. Shift transmission through all gear positions (P-R-N-D-M-L), pausing 3 seconds in each position. Return to Park.
   ⚠Keep foot firmly on brake pedal when shifting through drive gears to prevent vehicle movement.
9. 9

   Check fluid level and add as needed
   With engine running at idle and transmission in Park, remove dipstick and wipe clean. Reinsert fully, then remove and check level. Fluid should be in the crosshatch "COLD" range. Add additional fluid in 1/2 quart increments if needed until proper level is reached. Do not overfill.
10. 10

    Final level verification
    After test drive (see verification steps), recheck fluid level with transmission at operating temperature (160-180°F). Level should be in the "HOT" range on dipstick. Add or remove fluid as necessary to achieve proper level.

Reassembly

1. Ensure drain plug is torqued to specification with new crush washer installed
2. Verify dipstick is fully seated in tube
3. Clean any spilled transmission fluid from engine bay and undercarriage

Verification

• Check under vehicle for any transmission fluid leaks around drain plug area
• Test drive vehicle for 10-15 minutes to bring transmission to operating temperature and circulate fresh fluid
• After test drive, with engine at idle in Park on level ground, verify fluid level is in HOT range on dipstick
• Confirm smooth shifting through all gears with no slipping or delayed engagement
• Recheck for leaks after test drive while transmission is at operating temperature

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