I recently did my tranny. When I spoke with my dealer they used to use Redline MT-90, now they recommend BG Synchroshift II (costs $30/bottle from dealer or $120 CDN to change the fluid -- ripoff!)
There's some brief discussion about that here:
http://www.mazdas247.com/forum/showthread.php?t=123679012&highlight=synchroshift
That wasn't readily available and I read about Motomaster Formula 1 75w90 full synthetic from Canadian Tire on the toprotege forum (there were several threads about it), so I decided to give it a try for fun. As it turns out the shifts are reasonably smooth when warm, in the cold it's not as smooth. Another thread for your perusal:
http://www.toprotege.com/forums/showthread.php?t=48056&highlight=motomaster AFAIK the owner's manual states GL4 or GL5 gear oil, but I guess one may be better than the other.
Next time I will probably try the BG Synchroshift II with a little bit of Lucas oil stablizer.
Some tips/comments from when I changed the fluid -- make sure you remove the fill plug first, that way when you remove the drain plug, it will drain better. When refilling I didn't have any rubber hose handy, however, the 1L bottles had nice "squirt" type spouts so the fluid transfered quite fast, (I also used ramps). I wasn't able to completely empty the bottles so I transferred the leftover fluid into the last bottle and ended up putting in ~2.65 L overall (hence no need to completely dump in the last bottle).
If changing the fluid with the car leveled, just fill up till it just starts to overflow from the fill hole. But if using ramps remember not to put too much in due to the angle. The first time I ended up putting 2.75L and a few days later fluid was leaking from the top bolt so I had to drain some. Also inspect the crush washers, if they look too mangled be sure to replace them, or you may have leaks.
Is there anything else I missed?