Should I Change The Transmission Fluid?

My mother just bought a used 1994 Camry with 186,000 miles on it. I just talked to the owner to ask him when the last time he changed the fluids and timing belt etc.. He said that he has never changed the transmission fluid because he heard you weren't supposed to change the fluid in an automatic. I checked the fluid and it's pretty damn dirty. Anyway, I would like everyone's opinion as to whether it would be safe to change it at this point. The transmission changes fine, no problems at all. I know I've heard that once a transmission is going bad it's not a good idea to change the fluid. So, what do you think?

Each transmission is a separate case and you are rolling dice to some extent. If it were my vehicle, I would drain the fluid in the pan and replace what comes out with fresh fluid. This will only replace part of the fluid (a lot is kept in the torque converter and valve body) and give your existing fluid some needed additives. Then drain and replace what comes out again in around 10k miles, etc. This gradual change is, in my opinion, the best way to get your transmission some semblance of reliability.

The only other option, in my opinion, is to do nothing. I think the above gradual change is the better of the two.

Ok, this sounds like a good plan. Thanks!

You're welcome. Don't forget to also change the fluid in the differential. It uses ATF also. Just replace all of it. Don't bother trying to change part of it.