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2017 Q50 Red Sport 400 - Transmission Fluid Change Interval & Hard Shifts

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Mark S. · rep 0 · May 25, 3:50 AM · 1 replies · solved · Question

Vehicle: 2017 Infiniti Q50 Red Sport 400

Hey everyone,

I've got a 2017 Infiniti Q50 Red Sport 400 with about 70,000 miles on it. Lately, I've noticed some harder shifts, especially between 2nd and 3rd gear, and sometimes it feels a bit clunky when downshifting. I'm wondering if it's time for a transmission fluid change.

What's the recommended interval for the 7-speed automatic on these models, especially with the higher horsepower? I've seen conflicting info online. Is this something I can tackle myself, or is it best left to a shop? Any specific fluid recommendations or procedures for a DIY flush vs. drain and fill?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:50 AM

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ClearTheCode admin answer:

It's great you're paying attention to your transmission's behavior, especially in a performance model like the Red Sport 400. Hard shifts can indeed be a sign of aging transmission fluid.

  1. Recommended Interval: While Infiniti often lists transmission fluid as 'lifetime' or 'inspect only' under normal conditions, for performance vehicles or those driven hard, a proactive approach is best. Many enthusiasts and independent shops recommend a transmission fluid drain and fill every 60,000 to 80,000 miles for the 7-speed automatic. If you frequently drive in stop-and-go traffic, tow, or push the car hard, consider doing it closer to 50,000 miles.
  2. Causes of Hard Shifts: The primary cause is often degraded transmission fluid. Over time, the fluid loses its lubricating and cooling properties, leading to increased friction, heat, and sludge buildup. This can affect valve body operation and clutch engagement, resulting in harsh shifts. Low fluid levels can also contribute.
  3. DIY vs. Professional: A simple drain and fill can be a DIY project for those comfortable with basic car maintenance. It typically involves draining the old fluid from the pan, replacing the filter (if accessible and recommended for your model), and refilling with new fluid. A full flush, which exchanges nearly all the fluid, is usually best done by a professional shop with specialized equipment. Be cautious with 'power flushes' as they can sometimes dislodge debris.
  4. Fluid Type: Always use the exact fluid specified by Infiniti. For your 2017 Q50, this is typically Nissan Matic S ATF. Using an incorrect fluid can cause severe transmission damage.
  5. When to See a Shop: If the hard shifts are accompanied by slipping, grinding noises, or a 'check engine' light, it's crucial to have a professional diagnose the issue immediately. These symptoms could indicate a more serious internal transmission problem that goes beyond just fluid degradation.
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