I just wanted to add: I've read in multiple technical tranny rebuilt manuals, they indicate yer always better off replacing old fluid with new. Let's say worst case, after a change, it developed a shudder (not saying by any means it will...but let's just 'say'). If that occurred, you might then add an anti-shudder compound. It's designed to adjust the friction features of trans fluid. It's not black magic, Mopar and GM sell it for that reason.
Shudder occurs basically when friction values between the clutches or the torque converter are out of spec. It's not uncommon for high-mileage vehicles to develop shudder issues either normally or after a fluid change. Some after-market tranny fluid's for "High-Mile Applications" come 'pre-packed' with anti-shudder compound in their fluids (like Penzoil's Dextron's), to pre-emptively combat it in high-mile applications. And it works. Again, we're talking absolute worst-case here.
Another thing which can happen is shift solenoid's can flake out on RFE transmissions. I've experienced this ...and it seems like a bad tranny, but is a flaky shift solenoid. Once replaced it takes a couple days for the tranny to re-learn and smooth out. So *if* something does awray don't panic. It's a complex assembly of mechanical & electrical parts which can be diagnosed. But again, this is all just worst-case thinking here. Just trying to put things into perspective that things aren't binary in a transmission.
And *if* after you replaced your fluid the tranny WAS somehow permanently knocked out, let's say, it was undoubtedly hanging by a thread anyway. The new fluid didn't alone kill it.
I would not only change the fluid, I would exchange it. NOW having said that, I've seen some of these fluid exchangers, and one thing that worries me about them is how clean the *machines* are inside. And the hoses. Dealers usually put their new guys doing fluid changes, and their experienced technical guys doing highly technical troubleshooting. Everything should be super-clean from end-to-end in the fluid exchange process. A young kid worrying about the saturday night party and which of his buddies is picking up the latest CBD haul, isn't who I'd want making sure not a single aspect of heigyne is overlooked, on my vehicle.
