[AJD]

I've got a 2012 Tundra with the 6 spd Aisin tran as well. I did a fluid exchange (not Flush) about 20k mi ago when the truck had ~50k mi on it. I checked the condition of the tran fluid by loosening the check plug and it was just as black as yours... only a hint of red to it. I did a drain and fill with WS (almost 4 quarts exactly) and proceeded to toss and turn all night! lol. Couldn't believe how dark it was and have gotten the same "its forever fluid" from the dealerships as well. Guess they want to sell new 7k trans instead of a $200 fluid change. I took the truck to a local master Toyota/lexus shop and had them replace all ~12 quarts. They dont power flush by pumping the fluid into the trans, they disconnect the trans cooler line and let the trans pump out the old fluid while they pump in new fluid through the fill plug. No problems from this method so far. Will do a fluid change every 50k going forward as well. You could probably go 60-70k if you dont do any towing but I live in FL and tow a boat pretty often so for me its cheap insurance. If you have a truck with >100k on it, I would just do the drain and fill method. The tran is already broken in at that point, the clutch packs are worn and if you put in all new fluid it will often start slipping. Also I have been told there is no need to remove Gen 2 trans pans to replace the filter. The filter is more of a screen... no need to do if you are changing fluid regularly.

Agree the sealed system / no dipstick is a major pain... Wait till there is no oil dipstick! Yeah thats right, no oil dipstick and thats the direction its going. They are already doing it on some German vehicles. To check it its going to be the same type of procedure as the transmission is now, certain temp, open check bolt, wait for fluid stream, count the drips. Ridiculous. 🖕