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2018 Enclave Shuddering - Time for Transmission Fluid Change?

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David L. · rep 0 · May 25, 2:47 AM · 1 replies · solved · Question

Vehicle: 2018 Buick Enclave Premium

My 2018 Buick Enclave Premium with about 85,000 miles has recently started to exhibit a slight shudder, especially noticeable between 30-45 mph and sometimes during light acceleration. It's not constant, but definitely concerning.

I've heard about GM's 8-speed and 9-speed transmissions having issues and that a fluid change can sometimes help. What are the recommendations for this model?

Is this something I can tackle myself, or should I take it to a shop? Any specific fluid types or procedures I should be aware of?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:47 AM

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Hello David,

It's common for GM 8-speed and 9-speed transmissions (like the 9T50 in your 2018 Enclave) to develop a shudder, often related to the transmission fluid. GM has issued Technical Service Bulletins (TSBs) regarding this, often recommending a triple flush procedure with a specific updated fluid.

Causes & Solutions:

  1. Degraded Transmission Fluid: Over time, transmission fluid breaks down and loses its lubricating properties. The original fluid in some GM transmissions was found to contribute to shudder issues.
  2. GM TSB & Fluid: GM's recommended fix often involves performing a triple flush using ACDelco Dexron HP (High Performance) transmission fluid. This fluid has improved friction modifiers designed to eliminate the shudder. Simply draining and refilling once might not be enough; a triple flush ensures nearly all old fluid is replaced.

DIY vs. Professional:

  • DIY: A simple drain and fill can be done by a mechanically inclined individual, but a full triple flush requires specialized equipment (a fluid exchange machine) to cycle new fluid through the system while removing old fluid. It's also critical to maintain the correct fluid level, which often requires specific temperature monitoring.
  • Professional: For a proper triple flush, especially given the sensitivity of these transmissions, it's highly recommended to have a certified GM technician or a reputable transmission shop perform the service. They have the correct tools, fluid, and knowledge of the specific TSB procedures.

When to See a Shop:

  • If the shudder is severe or accompanied by hard shifts, delayed engagement, or warning lights.
  • If you're unsure about performing the complex flush procedure yourself.
  • If a simple fluid change doesn't resolve the issue, as it could indicate internal transmission wear or damage requiring further diagnosis.

Regular transmission maintenance is crucial, and addressing this shudder promptly can help prevent more costly repairs down the line.

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