You can use cough syrup if you want to, I suppose.
If you want lots of opinions, do a forum search as this has been discusses many many times
The short answer to your question is this; if you want to follow the manual, use Hy-Tran as it is what is recommended/required.
http://www.onlycubcadets.net/forum/s...ead.php?t=4634
That being said, there are many that don't use it, such as myself. A universal fluid (such as that from F&F or TS) should work without issue. At the end of the day, it's your machine so you can put whatever you want in it
Disclaimer: I don't mean to sound like a smart-a$$, I just have read through so many of the posts that I basically have a short and sweet answer memorized. Hope the above helped!