I have an '05 STi that I plan on running GC in once I hit 10,000 miles (that will be in 2,500 miles). Thus far I've run Mobil Drive Clean 5w-30 (UOA was done and posted), Motorcraft semi-syn 5w-30 (in the STi now, will be changed this weekend and sent off to Blackstone for analysis). I'll be trying Mobil 7500 semi-syn for the next 2,500 miles. So keep your eye out for my UOA with GC sometime in the future...I'd say probably sometime in July.