Transmission fluid flush

Hello, new member here. Thank you in advance!! I was talking to my mechanic about my wanting to get a transmission fluid flush and filter change. I have a 2016 5.7L 4wd flex. He mentioned that if the transmission fluid has never been changed then it might actually cause harm to change it now at 211k miles. Does this make sense to you guys?
Ty!!
Matt

 

Don't flush it, if you are going to change it, just do a single drain and fill. That'll change out ~4ish quarts, so you'll have some new ATF mixed in with the old, no major viscosity change, but some new fluid. Then repeat again at another 30-45K.

 

I'm in the same boat - 175k miles and never changed any transmission fluid...

 

Alot of shops won't touch it at that mileage if it hasn't been maintained. I would agree I did a drain and fill on an older trans that was never serviced, I needed a new transmission very quickly after i did the fluid. It shifted great before I touched it.

Also if you do anything just drain and fill. Trans pan bolts will probably strip/ break on your older truck. It's just a screen not a filter.

 

Drain and fill. Don't attempt to drop the pan, you will end up snapping the bolts and the filter is not worth changing.

 

Is it misbehaving?

Spoiler

I had mine flushed at dealer when she started washboard rumblestripping at 30-35mph and later right before downshift. She had almost 100k. Flush fixed the issue and brought her back to factory ride condition, on the second visit back to the dealer.

 

Its amazing how much better it shifts after a drain/fill