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Rough shifting and shudder on my 2018 F-150 3.5L EcoBoost - Time for a transmission fluid change?

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Mark S. · rep 0 · May 25, 1:35 AM · 1 replies · solved · Question

Vehicle: 2018 Ford F-150 Lariat

Hey everyone,

I've got a 2018 Ford F-150 Lariat with the 3.5L EcoBoost engine and about 85,000 miles on it. Lately, I've noticed some really rough shifts, especially from 3rd to 4th gear, and occasionally a slight shudder when accelerating at highway speeds. It's not constant, but it's definitely becoming more frequent.

I haven't changed the transmission fluid yet. The owner's manual suggests a service interval, but I'm wondering if this is a sign it's overdue or if there might be something else going on. No warning lights are on, and I haven't pulled any codes yet. Has anyone experienced this with their F-150? Is a drain and fill sufficient, or should I consider a full flush?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 1:35 AM

0

ClearTheCode admin answer:

It sounds like your 2018 Ford F-150's transmission might be showing signs of wear or low/degraded fluid. Given the mileage, a transmission fluid service is a very good starting point.

Causes & Diagnostics:

  1. Degraded Transmission Fluid: Over time, transmission fluid loses its lubricating properties and can become contaminated, leading to rough shifts and shuddering. This is the most common cause at your mileage.
  2. Low Fluid Level: A low fluid level can also cause similar symptoms. Check your transmission fluid level according to your owner's manual (often requires the engine to be at operating temp and level ground).
  3. Torque Converter Issues: Less commonly, a failing torque converter can cause shuddering. This is usually accompanied by specific diagnostic trouble codes (DTCs) like P0741 (Torque Converter Clutch Circuit Performance).
  4. Valve Body Problems: Issues within the transmission's valve body can lead to erratic shifting.

Recommended Steps:

  1. Check Fluid Level & Condition: Before anything else, check your transmission fluid level and observe its color and smell. Healthy fluid is typically reddish and clear, not dark brown or burnt-smelling.
  2. Transmission Fluid Service: For your 2018 F-150, Ford generally recommends a transmission fluid and filter change at 150,000 miles under normal driving, or sooner for severe duty. Given your symptoms, a drain and fill (or multiple drain and fills) is often safer than a full flush, especially if the fluid is very old, as a flush can sometimes dislodge debris and cause further issues. Consult with a trusted mechanic.
  3. Scan for Codes: Even without a check engine light, a pending code might be stored. Use an OBD-II scanner to check for any transmission-related DTCs.
  4. Adaptive Learning Reset: After a fluid change, some vehicles benefit from a transmission adaptive learning reset, which helps the transmission re-learn optimal shift points with the new fluid.

When to See a Shop:

  • If the symptoms persist or worsen after a fluid change.
  • If you find metal shavings in the drained fluid (a sign of internal wear).
  • If you pull any transmission-specific diagnostic trouble codes (e.g., P07xx series).
  • If you're uncomfortable performing the fluid change yourself, as it can be a complex procedure requiring specific fluid types (e.g., Mercon LV or ULV for newer Ford transmissions) and exact fill levels.
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