I personally use Motul x-cess 5w-40 or Lubro-Moly 0w-40. Amsoil is great but very expensive. Castrol and Mobile1 aren't that great for Supercharged or Turbocharged engines not to mention that all of the US made so called synthetic oils (except Amsolil) are a group III not a group IV as a real synthetic should be.
Are you guys noticing any differences when using these engine oils over others you may have used in the past?Motul X-Cess meets the specs required by Porsche from what I've read.
Perhaps then you'd address why Porsche bothers to give C30 Approval for Mobil 1 ESP Formula 5w30 and A40 Approval for Mobil 1 0W40. And I have to admit ignorance on the synthetic oil group business. What's that all about?Castrol and Mobile1 aren't that great for Supercharged or Turbocharged engines