well, found this video...not sure why it didn't pop up yesterday when I was looking on my phone:I have no idea...I can tell you that I just tightened the sh*t out of mine and then covered the entire area in sealant just to make sure everything is sealed. My rack has been there since 2012ish and hasn't leaked a drop.
https://www.youtube.com/watch?v=P9A580OpUoE
at 2:09 it shows a recommended torque of 55in/lbs, which is quite low. kinda surprised.