Dextron VI observation

[CheezWhiz]

2016 2500HD, 6.0 flex fuel engine and 6L90 transmission. 56k of very light usage, nearly zero towing but using 4x4 on occasion in the winter.

Changed the transfer case fluid and checked the transmission dipstick for the first time recently. Transfer case fluid was brown and nasty looking, fluid on the transmission dipstick looks new.

Not sure if it means anything at all, really, but I was surprised at the difference. The truck has a heavy duty trans cooler and transmission temps are usually below 130, so maybe that explains why the transmission fluid looks so nice.

In retrospect I’d have changed the transfer case fluid sooner, but I haven’t noticed any noise or other issues.

 

[wwillson]

I changed the transfer case fluid in my 2018 at 25,000 and found the fluid (Dex 6) was already discolored. These cases must run pretty hot running down the interstate.

 

[clinebarger]

The ATF will look different once it's drained into a pan, I would do a trans service....Pan drop, Clean the Magnet, & Change the Filter.

 

[JHZR2]

I don’t recall ever seeing anything that out of the ordinary with defer cases or ATF... but it always seems like front differentials in 4x4s get a bit funky over time.

 

[CheezWhiz]

The ATF will look different once it's drained into a pan, I would do a trans service....Pan drop, Clean the Magnet, & Change the Filter.

well i mean i know that’s what i should do ... there’s a lotta things i should do ...

 

[Oro_O]

The truck has a heavy duty trans cooler and transmission temps are usually below 130, so maybe that explains why the transmission fluid looks so nice.

That explains it. It's all about the temps when it comes to oxidation rates and wear from temps between the discs. If it really stays that low, you can buy a lot more time. A drain and fill (or pump a few quarts out the cooler return line if that's more convenient; it often is) would be smart, though. There is no "one size fits all" answer wrt fluid changes in any engine, transmission, or other system on a vehicle or other machine.