Best to DIY, lazyass dealers want to flush instead of drain and replace filter. I won’t consider it at less than 100k, but I’m not towing in a hot climate, so ymmv.
Sorry but I have to LOL at this. There is so much misinformation about this transmission its not even funny. Without getting into much debate here are a few FACTS that you need to know.
1. Ford doesn't even want the filter replaced during an overhaul unless there is metallic debris in it (usually only during catastrophic failure)
2. the torque converter holds several quarts of fluid that cannot be drained with a drain and fill, but will be replaced when doing a fluid exhchange (what you're calling a flush)
3. There is a thermal bypass valve that acts as a thermostat for transmission fluid to be routed to the cooler. A fluid exchange should be done at temperature to allow fluid flowing through the cooler to clean it out.
4. These transmissions can be extremely sensitive to fluid level. The level needs to be set with the TFT at 206-215F, also they use the same dipstick for several models and applications and there is a range on the stick where your particular vehicle needs the level set at. It can't just be "on the stick".
I certainly don't blame you for not wanting a particular dealer or technician to touch your vehicle. I don't let anyone else touch mine but I have access to a lot more tools, equipment and information than the average user. I would suggest investing in the proper tools, equipment and experience or finding someone you can trust that does.
Final thought..... I am a shop foreman at a Ford dealer. A lot of what I see every day is the "weird" stuff or hard to diagnose issues. I can't tell you the amount of time something becomes broken or damaged that I can point directly to someone (a customer or a mechanic friend or whatever) doing something extremely stupid. In my line of work I see the uncommon failures, the customer that drilled a hole in their RCM trying to install rock lights throwing an intermittent airbag light, the shop that installed a tow bar to tow the car behind their RV that "rerouted" some wiring and it chafed on the edge of the radiator causing multiple electrical issues, and the "mechanic friend" that helped someone do a transmission spill and fill that put the wrong fluid in (way too thick, ULV stands for ultra low viscosity and this stuff was not) which ended up causing catastrophic internal failure (yes that actually happened).
-Joe
