Is Dexron ULV Behind GM’s New Vibration Bulletin? What the Data Suggests — And What #25-NA-369 Actually Says - 10L80

Released December 4, 2025

Applies to 2021–2026 Silverado, Sierra, Tahoe, Suburban, Yukon, Escalade (LM2 & LZ0, MQB/MQC 10-speed)

GM’s newest bulletin, #25-NA-369, addresses a vibration or “shudder” felt at steady speeds between 25 and 80 mph. Before diving into the bulletin details, it’s important to understand why this issue often gets tied back to Dexron ULV, the ultra-low-viscosity transmission fluid used in the 10-speed (MQB/MQC) found behind the 3.0 Duramax.

And while GM never states that ULV is defective, the behavior of the fix — and the sensitivity of this transmission to fluid condition — raises fair, technical questions.

This article explains that connection first, then gives the complete and accurate breakdown of everything GM outlines in the bulletin.

Why Dexron ULV Comes Up in Discussions of 10-Speed Shudder

The bulletin does not blame ULV fluid, but the repair strategy strongly suggests that fluid condition plays a major role in torque-converter shudder.

Here’s why:

1. The mandated fix is a 20-quart, triple drain-and-fill using only Dexron ULV.

A flush this aggressive is used when the existing fluid:

• has sheared down,

• has lost friction modifiers,

• is contaminated, or

• no longer provides the correct clutch-apply characteristics.

These are signs of fluid degradation, not mechanical failure.

2. GM prohibits mixing ULV with any other fluid or additives.

This indicates the TCC is extremely sensitive to ULV’s friction profile.Even slight changes can allow the torque converter clutch to slip under load and feel like shudder.

3. GM says improvement is “directional” immediately and fully resolves by 200 miles.

That is classic reconditioning behavior: fresh fluid gradually restores the friction surface.

4. The bulletin exists despite low actual failure rates of the converters or pumps.

This further suggests that shudder on these transmissions is often a fluid-behavior issue, not a mechanical breakdown.

5. Many real-world complaints occur on vehicles used for towing or in high-heat environments.

Those conditions accelerate viscosity shear and additive breakdown — both significant factors in ULV fluid life.

Now Let’s Break Down the Actual Bulletin: #25-NA-369

After addressing the ULV question, here is the full explanation of what the bulletin states and how GM wants technicians to diagnose and correct the concern.

GM Bulletin #25-NA-369: Vibration Between 25 and 80 MPH at Steady Speed

Condition

Customers may report:

• Vibration between 25–80 mph at steady speed

• Vibration worsened when climbing mild grades

• More noticeable vibration when towing or hauling

• A sensation similar to torque converter shudder

This is why the ULV discussion above matters — shudder and general vibration feel very similar from the driver’s seat.

Misdiagnosis Is Extremely Common

GM stresses that many “shudder” complaints are not torque-converter issues.

Other causes frequently produce the same sensation:

1. Ride height changes / excessive tongue weight

Alters pinion angle → induces driveline vibration.

2. Engine performance concerns

Misfires, poor fuel quality, or torque loss can mimic converter shudder.

3. Exhaust grounding or misalignment

Crushed crossover pipes and poor exhaust hanger alignment can amplify vibration during AFM operation.

4. Engine or transmission mount issues

Debris (stones, mud) in the transmission mount is specifically mentioned.

5. Radiator grounding or misalignment

The radiator normally damps vibration; when grounded, it transfers vibration into the vehicle structure.

GM notes that all of the above are commonly mistaken for torque converter issues.

Diagnostic Requirements: GDS + PICO Scope

To separate true TCC shudder from unrelated vibrations, GM requires:

GDS Graphing

Used to confirm whether the torque converter is applied during the event.

PICO Scope Vibration Analysis

Used to identify the transfer path of the vibration.Sensor placement examples:

• Frame areas near engine/trans mounts

• Exhaust hanger brackets

• Radiator support structure

This step is essential. GM emphasizes that PICO must be used, especially when evaluating mount isolation.

When the Torque Converter Is the Problem

If diagnostics confirm torque-converter shudder:

GM mandates a triple drain-and-fill fluid exchange with Dexron ULV.

High-level summary:

• Use the DT-45096 TransFlow machine

• Exchange 20 quarts in controlled 4-quart cycles

• Follow SI exactly

• No additives

• No mixing of fluids

• Final level-set procedure required

• A minimum of 2 cold-to-operating-temp cycles before full resolution

GM notes the customer should expect full improvement by 200 miles.

If shudder remains and diagnostics still point to the converter → then replace the torque converter.

Parts and Warranty

Parts Required

• 20 quarts ULV fluid (19352619 / 19352620)

• One oil cooler line seal (85628205)

Labor Operation

• 8481288: Triple Drain & Fill (2.0 hr)

• +0.2 hr for front driveshaft separation (4WD)

Coverage applies only during Powertrain Warranty. VIN must be checked in IVH.

What Owners Should Do

1. Document conditions when vibration occurs.

2. Ask for a full vibration diagnosis, not just a quick converter call.

3. Understand that many cases are not torque converter issues.

4. If ULV exchange is performed, allow 200 miles of driving.

5. If the concern persists, request follow-up diagnostics before considering mechanical replacement.

   
   

This bulletin is a strong indicator of how sensitive the 10-speed’s torque converter clutch is to fluid condition, even though GM stops short of labeling ULV as the root cause. The repair path — especially the reliance on a 20-quart ULV exchange — shows that restoring the correct friction profile is often the solution.

At the same time, GM makes clear that many so-called “shudder” complaints have nothing to do with the converter and must be diagnosed thoroughly using GDS and PICO before repairs begin.

The combination of both messages — fluid sensitivity and frequent misdiagnosis — explains why this bulletin is so detailed and why GM is pushing structured diagnostic steps.