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2018 MKX Transmission Fluid Change - Is it really 'lifetime'?

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Laura J. · rep 0 · May 22, 6:09 AM · 1 replies · solved · Question

Vehicle: 2018 Lincoln MKX Reserve

Hey everyone,

I've got a 2018 Lincoln MKX with the 3.7L engine and about 75,000 miles on it. I've been doing all my regular maintenance, oil changes, tire rotations, etc., but I'm starting to wonder about the transmission fluid.

I've heard some people say that modern transmissions, especially in luxury cars like Lincoln, have 'lifetime' fluid and don't need to be changed. Is this true for my MKX? I plan on keeping this car for a long time, and I want to make sure I'm doing everything right to extend its life.

What's the general consensus here? Should I get the transmission fluid flushed or just a drain and fill? Any specific fluid recommendations or things to watch out for? Thanks in advance for any advice!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 6:09 AM

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ClearTheCode admin answer:

It's a common misconception that modern automatic transmission fluid (ATF) is truly 'lifetime.' While manufacturers often state very long service intervals or even 'sealed for life,' this typically refers to the expected lifespan of the first owner or a specific mileage under ideal conditions. For long-term ownership, especially beyond 100,000 miles, proactive transmission fluid maintenance is highly recommended for your 2018 Lincoln MKX.

Here's what you should consider:

  1. Check Your Owner's Manual: Always refer to your specific owner's manual for the manufacturer's recommended service schedule. While it might not explicitly state a change interval, it often has a 'severe duty' schedule that applies to most drivers (e.g., frequent towing, heavy city driving, extreme temperatures).
  2. Why Change It? Over time, ATF breaks down due to heat and friction, losing its lubricating and cooling properties. It also accumulates wear particles. Old fluid can lead to harder shifts, reduced fuel economy, and eventually, costly transmission damage.
  3. Drain and Fill vs. Flush:
    • Drain and Fill: This is generally safer and recommended for higher mileage vehicles that haven't had regular fluid changes. It replaces only a portion of the fluid (typically 4-6 quarts out of 10-12 total) but avoids dislodging debris that a high-pressure flush might. You might need to do a few drain-and-fills over several thousand miles to replace most of the old fluid.
    • Flush: A full fluid exchange can be beneficial if done regularly from a lower mileage. However, if your fluid is very old and dark, a flush can sometimes dislodge sediment that then clogs internal passages, potentially causing issues. Consult a trusted mechanic.
  4. Fluid Type: Your 2018 Lincoln MKX (with the 6F50/6F55 transmission) requires MERCON® LV Automatic Transmission Fluid. Using the correct fluid is critical for proper transmission operation and longevity.
  5. When to See a Shop:
    • If your transmission is exhibiting symptoms like slipping, hard shifts, delayed engagement, or unusual noises, get it inspected by a professional immediately. These could be signs of advanced wear, and a fluid change might not be the solution or could even exacerbate an existing problem.
    • If you're unsure about performing a drain and fill yourself, or if you opt for a full flush, a reputable shop with proper equipment and experience with Lincoln vehicles is your best bet.

For your 2018 MKX at 75,000 miles, a drain and fill with MERCON® LV fluid is a wise preventative measure. Consider repeating it every 30,000-60,000 miles, especially if you drive in conditions that fall under 'severe duty'.

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