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2018 Q50 Red Sport - Rough Shifting After 60k Miles, Transmission Fluid?

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Kevin B. · rep 0 · May 22, 5:09 AM · 1 replies · solved · Question

Vehicle: 2018 Infiniti Q50 Red Sport 400

Hey everyone,

I've got a 2018 Infiniti Q50 Red Sport 400 with about 62,000 miles on it. Lately, I've noticed some really rough shifts, especially when downshifting or accelerating moderately. It feels like the transmission is hesitant and sometimes clunks into gear.

I'm wondering if this could be related to the transmission fluid. I know Infiniti transmissions are often considered 'sealed for life,' but 60k miles seems like a point where fluid might start to degrade, especially with the higher performance of the Red Sport.

Has anyone else experienced this with their Q50 around this mileage? Should I be looking into a transmission fluid flush or drain and fill? Or could it be something else entirely, like a sensor issue? Any advice on DIY checks or what to tell a shop would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:09 AM

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ClearTheCode admin answer:

It's understandable to be concerned about rough shifting in your 2018 Infiniti Q50 Red Sport 400, especially at 62,000 miles. While Infiniti often states their transmissions are 'sealed for life,' many enthusiasts and mechanics recommend a transmission fluid service around 60,000 to 90,000 miles, particularly for performance models or vehicles driven under severe conditions (towing, frequent stop-and-go, aggressive driving).

Here's what could be causing the issue and what you can do:

  1. Degraded Transmission Fluid:

    • Cause: Over time, transmission fluid breaks down, losing its lubricating and cooling properties. This can lead to increased friction, heat, and poor shifting performance. The Red Sport's higher power output can accelerate this degradation.
    • Action: A drain and fill (not a flush, which can sometimes dislodge debris and cause more issues in older transmissions) with the correct OEM-specified fluid (Nissan Matic S or equivalent for your 7-speed automatic) is often beneficial. This is a DIY-friendly task for those comfortable with car maintenance, but ensuring the correct fluid level and temperature during filling is crucial.

  2. Low Transmission Fluid Level:

    • Cause: Even in 'sealed' systems, minor leaks can occur, leading to a low fluid level. This can cause erratic shifting, slipping, or harsh engagement.
    • Action: Checking the fluid level on these transmissions can be tricky as there's often no traditional dipstick. It typically involves checking a fill plug with the transmission at a specific operating temperature. This is best done by a professional if you're not familiar with the procedure.

  3. Transmission Solenoid or Sensor Issues:

    • Cause: Faulty solenoids (which control fluid flow) or speed sensors can cause incorrect gear engagement or delayed shifts.
    • Action: If a fluid service doesn't resolve the issue, a diagnostic scan for transmission-related trouble codes (e.g., P0700 series codes) would be the next step. While you might not get a Check Engine Light, a dedicated transmission scan tool can often reveal pending or specific transmission control module (TCM) codes.

When to See a Shop:

  • If you're uncomfortable performing a transmission fluid drain and fill yourself.
  • If the rough shifting persists after a fluid service.
  • If you notice any leaks under the car.
  • If you experience any warning lights on your dashboard (even if not directly transmission-related, they can sometimes be linked).
  • If a diagnostic scan reveals specific transmission fault codes.

Addressing this promptly can prevent more significant and costly transmission damage down the line.

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