Never used before coz:how bout HKS FS? i've been using em for about 3 times before switching back to SS since i'm not driving hard enough to fully exploit the lube...
1. Too expensive
2. No idea who actually made these oil.
3. Read some forums overseas (US & Europe) that it doesn't seem that good/not having good reviews especially considering the price.
In short, not really confident enough to try it.