It's been a while, but I remember back when Subaru's recommendation was solely for GL-5 75W90. I'd tried all sorts of lubes including Red Line 75W90NS and Motul Gear 300. I did have this really odd reverse gear failure back in 2010 but I can't attribute that to the gear lube. Someone I know actually rebuilt it because he couldn't find a used or rebuilt transmission and handed me the reverse idler gear that had a couple of broken teeth as well as a few bent ones. Said it was highly unusual for straight gears to break. But he had access to Special S and I believe that's what's still in there. I haven't bothered to change it since since I'm kind of lazy and technically they only say to inspect it and change if there's an issue. It's not low so I haven't done anything. Shifts are still good. I'd like to change it again if I could get Special S, but not sure if it's still available and I can't find my tools - especially that oddball T-70 Torx bit. Do they still use that?
You cannot get Extra-S anymore, so unless you find someone with part of a pail left, you are out of luck. I believe its still the Torx bit, but might be different depending on your year.
I've tried the Redline 75W90NS, and while good, it was not as good as the Motul Gear 300.
The Motul is what I use in every Subaru diff I own or service (that number is now at 9 vehicles and counting); for 4EATs I use MaxLife ATF in the tranny but still Motul in the diffs. It's worth every penny.
Thanks for the advice, thats good to know. I have heard good things, but wasnt sure how it behaved in the 6 speed.
Redline, or ask on a Sube board.
You know how oil threads go. Thats why I figured I would ask on an oil board. Plus the most active seems to be NASIOC, and I dont want their snark or to hear about Uncle Scotty's Cocktail any more.