[Aredubjay]

Well, about the BEST way to flush out the old is a
T-Tech or similar, tranny flush. Some Subaru dealerships have the T-Tech equipment. Other shops (I used a Penske Shop) have similar equipment (Penske uses the Snap-on equivalent). However, before you have any tranny flush done, make sure they're using a system that uses your own transmission to provide the circulation to take the old fluid out, and not a system that uses "the systems" pressure to flush the tranny.

As a side note, there are those who would say that a full tranny flush of this type may be harmful. Some say that the procedure dislodges accumulated particulates that may clog your cooling lines and cause eminent failure. Of course, using burnt fluid with suspended particulates (however minute) will also lead to eminent failure.

To my knowledge, however, I don't know of anyone who can actually attribute a tranny failure to this procedure.

Just thought I'd give you the pros and cons. Now, if you're adventurous, once the Yahoo database is fully available, you can do a "tranny search" -- there were a couple of guys on the yahoo board who used (for lack of more technical terminology) a "funnel and bucket" flush method. According to them, it was messy but effective.

So, now you have it. Sorry for the long post. Oh, and just for general knowledge. If you do a simple drain and fill, you can expect to drain about 6 quarts of fluid, which is only half of the capacity. You'll be adding fresh fluid to approximately 6 quarts of "rancid" fluid.