Well the topic drifted to AT fluid above, hopefully everyone changes their oil
When I say it looked bad at 18K, I didn't get an analysis done, but that wasn't just color either. You can feel the difference slipping the fluid between your fingers, between fresh Nissan Matic-S ATF and the stuff in my car. It's not real fluid analysis, but it's not useless either.
The only reason I even noticed is because I was installing an ATF fluid cooler at the time, so I had to buy an extra quart or two to fill up the new capacity, and disconnect the lines and see the old fluid in the install process. I did the cooler install at home by pre-filling the cooler core and most of the new line length, and being very careful about capping things off and minimizing spills during the hose hookups. And then I took it to the dealership for something unrelated a couple weeks later and had them swap the fluid and re-set the level perfect.