Denali Drivetrain noise when in AUTO

[300 Blackout]

I'm planning on swapping both diff. fluids as well as the transfer case soon to see if this will help.  Any advice on what brands or weights that I should go with would be appreciated. 

 

I went with AMSOIL Severe Gear 75W-90 for my diff fluid and AMSOIL Signature Series Fuel Efficient ATF for my trans and transfer case. Become an Amsoil preferred customer if you’re gonna drop that amount of money on Amsoil fluids. It’s a no brainer as it will save you more than the cost of the membership and includes free shipping etc... Nick (Black02Silverado) can get you squared away if you choose to go that route.

 

There’s plenty of other great options out there too, hopefully others will chime in.

[mongoose71]

Yesterday I changed the front Diff with Mobil 1 Synthetic 75w-90 and the transfer case with Royal purple synthetic ATF.  Both of the fluids still had great color and the magnets had minimal filings on them compared to some pictures/videos that I've seen online.

 

On my way to work this morning I Swapped the transfer case selector to Auto and I still have the noise that I've described. I'm assuming that it is the Module as some on here have suggested.

 

On a side note, I'm planning on changing the Rear Diff Fluid soon.  Rather than removing the cover and dealing with the gasket, I may pump out as much of the fluid as I can and refill it.  I may use Mobil 1 or Amsoil sever gear for this job. 

[pronstar]

 
 (From GMCs Website)

Although not always optimal for efficiency and wear of your vehicle 4wd driveline, AUTOMATIC 4 HI can be used on any road condition without risk of damaging your vehicle.


Interesting wording.

It will wear things out faster, but won’t damage your vehicle.


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[2018GmcSierra1500]

Just bought a 2018 GMC Sierra 1500. In 2wd I have a moan coming from front driver side. Anywhere from 30-50mph+. Mainly when giving it gas. Switch to auto and starts shaking and much more noises. My previous 2012 you could switch and not notice a bit of difference. My dealer claims “road or tire noise”. Im half deaf and can hear and feel it. Hopefully you figure it out as Im about to take mine back in with less than 500 miles on it. That’s right 500, not 5,000