Originally Posted By: momomeister
Below is a copy and paste from Castrol's site (with the section referencing API bolded by me):
SAE 0W–30:
Castrol SYNTEC 0W–30 European Formula is engineered to meet the Mercedes Benz 229.5 specification. The 0W–30 viscosity grade is ideal for winter conditions where low temperature pumpability is required. A unique, low–temperature formulation provides exceptional pumpability in cold weather and allows for unaided engine starts down to –40ºF. Exceeds all car and light truck manufacturer's warranty requirements for the protection of gasoline, diesel and turbocharged engines where API SL, SJ, SH, CF or CD is recommended. Exceeds European ACEA: A3, B3, B4; VW 502 00, 505 00, 503 01; MB 229.1, 229.3, 229.5; BMW LL–01; GM–LLA–025, GM–LL–B–025 and the engine protection requirements of ILSAC GF–3 for API Certified Gasoline Engine Oils.
So, according to this, GC does not meet the requirements of SM. This is a good thing, in my opinion. Matter of fact, I am presently using M1 10W30 HM in my Pathfinder because it is still SL rated and has a stronger add- package than regular SM Mobil 1.