Pretty sure my dealer screwed me! I wanted my transmission flushed on My 19 F250 gas 4x4 with 25k miles. when I brought it back home I got under it to service the transfercase and saw that the screw in dipstick was touched but i can't find any evidence that any of the cooler lines were removed and tapped into no salt and dirt was disturbed anywhere. most will say 25k isn't enough miles but the truck plows snow and carries a two yard salt spreader. can you drain and fill from the dip stick? the oil didn't look bad when i checked it but it wasn't Hot pink like the fresh oil is for the transfer case. I went back to the dealer and talked to the service writer and manager and they claim the tech did it but i just don't think he did. Probably $230 down the drain.

 

If the 6R100 is anything like the 6R75/80 that I’m used to with the Expedition the transmission cannot be flushed according to owners manual. There is a thermostatic valve that will not allow flow to the trans cooler until 190 degrees is hit so most times flushes paid for aren’t really done or they just flush out the lines themselves. Generally on the 6R75/80 the procedure is to drop the pan and replace the filter which gets 7-8 quarts or so. Sorry I’m not more knowledgeable on the 6R100 just sharing what I know from the lighter duty 6 speed.


I believe the 6R100 has a proper drain through the pan so you don’t have to drop the pan out like the 6R80, you should be able to drain and fill it easily.

 

Thank you They Definitely didn't drop the pan!

 

Sure you can drain and fill from the dip stick tube. On a lot of vehicles, that is how motor oil is changed. If all you were doing is just changing out the fluid without a filter change, then that's how you do it. But you were talking a flush, which is different from just changing fluid. A flush would be pumping new fluid/cleaner throughout the system to include the converter and valve body. A flush is generally not necessary and while most shops call it a fluid flush, it's actually a wallet flush. I understand your concern is some pretty severe operating conditions and a fluid change would be good PM, a system flush only if something showed up when sucking out the old fluid.

 

Won’t know it’s done properly unless you do it yourself.

 

You can get almost half of the fluid out with that method.

A flush can also just be a fluid change. I would never allow those snake oil chemicals in my transmission.
Here is a great way to change all of the fluid in a 5R110W. With some minor changes, it would work on a 6R transmission. It gets around the thermostat problem.
https://www.ford-trucks.com/forums/1...-exchange.html

 

The Mercon LV can't be judged by color, this is well known and there is a field bulletin about it. The Fluid will start discoloring above 200 degrees it's normal due to the vocal in the dye. The 6R100 is only serviced by pan drops or a special flush adapter which bolts on to the cooler line block. Most dealers don't have it because there isn't a huge demand. A simple pan drop and fill would be fine. Pulling a fluid sample and sending it for testing would also help you baseline future changes.