i just changed my tranny oil from dino to redline it feels great. that sti 6 speed though needs the lsd additives . research it man but in my opinion its all about the redline.they make the stuff you need . i was having an issue with the 5 speed , when cold first to 2nd would grind , syncros not lining up / slowly like real slow, but the redline has the 5 speed feelin sweet. smooth engadgement. you must shift like insane with a 6 speed i would definatly say you want the redline esspecially living in so cal and summer comin up. plus redline wont void your warentee not that any dealer really honors it anyway.