XT5 dark trans fluid drained at 31k mi

[nascarnation]

Not too many folks here are doing oil analysis on ATF and it's been 18 years since I did any at work, but I'd expect Dex VI to be good for 100,000 miles if the typical operating temp was 220f.
I can't comment on the color other than there are posts about trans fluid turning dark from anti-rust coatings applied to the internal components for storage/transit at the factory.
If you're really concerned, put in something that meets Allison TES-668 and you'll be in great shape.

 

[MurkyAsparagus]

For everyone here wondering about changing out the filter; these 9Txx transmissions do not have a serviceable filter, the filter is internal to the transmission casing.

9T50 is practically the same as the 9T60 I have in my '23 Blazer. I plan on a service every 25-30k miles using Dexron VI full synthetic transmission fluid. It's an extremely simple process to do a drain and fill, only need a new drain plug which is readily available from RockAuto. I see some use a Votex magnetic drain plug.

I've looked around and don't see many failures before ~100k miles or so. Those that post failures often say the transmission was never serviced. The key to these transmission is clean fluid changed early and often.