GC (German Castrol) is probably the best stuff we can use for our SR20's, it is Castrol Syntec 0w30 and it says made in germany on the back. It is a group IV synthetic (like Amsoil) and is more like the US made 5W40 oil.
Was using M1 10w40 but saw very high oil temperatures on the track (250-260 deg F on a 60 deg F days).
I just did a switch on my VE, I put 1L of Syntec 5w50 and 2.5L of GC as I will be primarly tracking the car.
Ohh I forgot, my SR20DE rod blew on the track with Mobil1 10w30 last year!