Re: 2016 Limited LTZ transmission fluid change
Black fluid, as long as it does NOT smell burnt, does not necessarily imply anything. Calling the fluid color black is also, to a certain extent, a judgment call. Dark brown is usually a more accurate description and that is normal. If you see any metallic appearance however I would be concerned. The fluid will not retain it's red color for long. IMO, there is no such thing as lifetime fluid. Now with that said, the fluid doesn't wear out, but the additive package will be consumed at some point and at that time the fluid needs to be changed.
Fluid level is critical, too much would probably be the one I'd be more concerned with, however, too little is more common in my experience. If you do your own service and you measure what you remove and then add in the same amount, you're back to where you started with fluid level but you still don't know whether that level is correct. In regards to the 6T40, as an example, the temperature you're supposed to check level at is around 190 degrees, ATF temperature that is, not coolant temperature. Also keep in mind, some of the late model transmission cooler lines have thermostats in them which blocks off cooler flow until trans temp is high enough. That is important as if the cooler circuit is not full of fluid when you set the level, when the thermostat does open the air will be purged from the cooler and your fluid level will drop, most likely not a lot but a drop none the less. Yes, it's a PITA to go through all the steps to set proper fluid level but these transmissions aren't the turbo 350's of 40 years ago either. Just my 2 cents.