Well Captain I have run the Castrol gold bottle with very positive results. It has run very well in my Fusion and Altima. It's funny that the Castrol msds is very secretive in what makes up their "highly refined" base oil. I'm not knocking them at all for that. It's just interesting compared to their 0w40 and 0w30 msds which do specify what's in those oils. I may be wrong but it could be that the gold bottle is their gtl version of full synthetics. The gold bottles meet ACEA A1/B1, Dexos, and HTO-06. I strongly suspect that it still meets the ACEA A5 gasoline side of this specification but they haven't made the adjustments to help it make the B5 diesel part of this specification. It's also possible that they have made the changes needed to pass it but haven't submitted it for testing to pass it just yet.
Given the very good results with the Magnatec version I would believe it's more than capable of running up to 10k miles. Very good TBN retention and viscosity retention makes this very possible. Plus added that you are running wide open highway driving 90% of the time than this would lead to it making 10k miles. Plus the recent discussion of the Dexos specification testing could very likely result in this oil being 75% synthetic. Which means this oil is a fine buy at $18 plus tax for a 5 qt container at Walmart.