To the OP, I am with Mark, get a flush.
You have to understand that coming from me that is saying a lot because I used to really carry on about not doing a flush. The newer flush machines do a pretty good job and get most of the old fluid out with a whole lot less chance of messing things up worse than when you started.
On the 180k mile transmission. Its a crapshoot.
Remember that the Dr Tranny stuff is a friction modifier and not some magic concoction. It won't fix a problem, but it will mask the symptoms for a while. If you are going to use that only do it as a last resort after doing everything else you can. If you have to use it then you need to start saving up for a rebuild immediately.