Just a quick question, Have an 07 STI with 12k miles on it. I changed out the gear oil to M1 early on and have had great results, however my question is: Is or Can the the STI (07) take a Posi additive added to the rear diff to quiet down the LSD? The LSD I know makes plenty of noise at slow speed pulling into parking spots etc. I already know why the STI's LSD's are noisy. My buddy though Just changed his gear oil to AMS OIL all the way around and added some GM posi LSD additive to the rear diff. He tells me now that the noisy LSD is a LOT more quiet now. I'm planning to switch to AMS oil in the next 2k miles and I just wanted to see if you really are supposed to add an LSD additive to the rear diff, or if just putting a good synthetic gear oil by itself will be fine. My guess is they don't put an additive from the factory cause it has been noisy on tight turns at slow speed ever since I got the car brand new. That gear oil Subaru puts in the factory is pretty much garbage anyways. I got my car in Novemeber, and the synchros were notchy as hell. As soon as I switched to M1, everything has been very smooth ever since. Let me know about the LSD thing though guys. Thanks in advance.