Mobil 1 0W-30, but thinking of switching to Castrol Syntec 0W-30 (made in Germany) if I can find it.
Son has some in his ZTS. MPG and butt dyno noticably down. This 30W is on the upper end of the 30W scale (compared to Mobil1 for example)and does not thin out. Great oil IMO, but not in this aplication