I've always used Castrol Syntec. Nothing else has gone in there.
I leak, but for some reason whenever I check the dipstick it reads the same
so it must be a verrrryyy ssssllloowwww leak from the top.
I used 92 Premium until it was no longer available due to "health reasons" and importation costs. I now use 90 with a double dose of octane booster with some success.
Got my tranny cooler from AutoZone over the internet. (: