Have purchased 2011 Golf. Not understanding why Castrol Edge 5w/40 Turbodiesel would not be preferable to Castrol 5w/40, non-specified. TD Edge appears from web articles to be more applicable to older pumpe duse engines. Manual is little help as it specifies only Spec 507 synthetics. When asked the same question the service manager could not answer. Not exactly a confidence builder in VW technician training. Thanks for any help on this. I will also call Castrol.