I thought that ADM standard WRX's had open diffs, Foresters a plated rear LSD.

Mine has a 2 way mechanical LSD and an standard open front diff. The Torsen type rear LSD gives excellent traction in the wet, gravel, sand or if one wheel comes off the bitumen, eg rally cars. BUT it wears out tyres, just rolling down a slope and turning the wheel 1/4 turn will stop the car. It tries to push the car in a straight line when locked up. It also only acts as a LSD if both wheels are loaded. When pushing it if one wheel comes off the ground it reverts back to behaving like an open diff. Plated and viscous LSD's don't have this fault. Open or LSD they all have their good and bad points and they can be fussy about having the right oil.

GC8 wrx's have open front diffs with viscous rear LSD's.

Gc8 STi's have open front & Suretrac LSD rear.

The oil type for Viscous makes no difference - the Viscous unit is a sealed assembly.

__________________
[CENTER][SIGPIC][/SIGPIC][/CENTER]
[CENTER][COLOR=#ff0000]Built Ej207: Semi-closed RA Cases - Wiseco Forgies - Manley rods - BC 272 cams - GDA Heads - billet f/whl - Vi-pec - WbO2 - 800cc Yellow tops - TD05-20G - 409Hp ath @ 1.75bar on E85[/COLOR][/CENTER]

Great, Rosco had the missing STi answer.
Unless you have a traction problem a front LSD might not be much use. A LSD will try and turn the front wheels at the same or a simular speed, this is good in a straight line, but when cornering it will increase the Subie understeer.
When hammering it around a corner what would help would be a bit of light brake pressure on the inside front wheel to try and slow it a bit and speed up the outside front wheel. This would improve the handling more than a front LSD. Unfortunately not an option on the older Subies. Maybe the new ones have it along with all the other electronic aids.
Didn't get specific with the diff oils as if I write too much or take too long writing it, it doesn't post. Just doing this to get my posts up so I can access other areas.

Most LSD front diffs (if not all) are only a of a limited lock design, due to the steering issues that would arise as you have described.


Where is your intro thread?