^^The cocktail being referred to here is called "Uncle Scotty's Cocktail", after the user/Subaru-guru "Uncle Scotty" on the Nasioc forums who came up with it. It works really well with the 5 speed subaru 'boxes. I use a variation to it ........and since I first put it in, I've been sold.
However, the cocktail is NOT recommended for the 6 speed boxes. One of the ingredients (Redline Shockproof) contains a "solid" particles (for want of a better description) which can mess up the fluid circulation system and filter inside the 6 speed 'box. It doesn't mean that it won't work....it will....but there is a long term risk).
(The 5 speed uses splash type lubrication, the 6 speed uses more of a "circulation" type system, with a filter in the 'box).