Fluids! Clear the confusion. What are you using?

[Thrust]

Agreed, I used 75W-90 in both.

 

[SuperOldSchool]

Don’t overthink it, just get fresh fluid in it.

Used Amsoil 75w90 on both. Have changed it twice:

2015 Yukon - Change both diffs' oil and transfer case fluid early on

Just sharing my experience with everyone. 2015 Yukon Denali with 39k miles. I changed the gear oil in both differentials and the transfer case fluid today. Used Amsoil Severe Gear 75w-90 and their Synthetic ATF, which is compatible with Dexron VI. I wish I had done this at 5k or 10k...

www.tahoeyukonforum.com

Trans needs new fluid. Did mine at 45k, 84k, 100k:

Changed my filter and fluid on 8l90 8 speed today

I followed a YouTube video and changed my 8l90’s filter and fluid today. I had dealer do the first time at 45k. 34k later it’s my turn. I bought a fluid extractor to suck most out of the pan first. The most time consuming step was getting the darn heat shield removed. The rest was easy. I...

www.tahoeyukonforum.com

Flush brake system:
https://www.tahoeyukonforum.com/threads/don’t-forget-to-flush-your-brake-system-3yrs-or-45k.101226/

Plugs changed:

Replaced plugs and wires at 76k - 2015 Denali

Hello Sharing pics of plugs at 76k. Changed wires as well. Manual states 97,500 miles to do this, but I tend to do routine maintenance early, since I don’t drive in ideal conditions. Waiting until 100k might also make it hard to get plugs out... They look great. Probably no issues going...

www.tahoeyukonforum.com

 

[rdhogg]

my confusion mostly was with the front diff information. The book says 80w90 but I can’t find any videos tutorials or websites that recommend 80w90 for the front. It’s all 75 90. Wondering if GM changed specs after a couple years?

...and remember back in the day you could order complete maintenance manuals for your ride ( didn't cost that much) and they reminded you that you had to replace the 'blinker fluid' when needed.

 

[steiny93]

So if y’all wouldn’t mind helping me out and steering me in the Right direction that would be awesome.

And what brands do you guys prefer?

Run fluids which are compatible with what the manufacturer recommends, feel free to exceed spec if applicable (dexron III instead of dexron II or synthetic instead of dino as examples).

Beyond spec, brand doesn't matter. You aren't going to 'save an engine' by running Mobile1 vs Amazon 5w-30 for example.

 

[Marky Dissod]

In any situation where 5W30 motor oil is called for, 0W30 is either perfectly acceptable or superior.

If 80W90 gear oil is called for, why would 75W90 gear oil not be either perfectly acceptable or superior?