Cressida, I think the guy's evasiveness was based more in the restrictions placed on Shell by the deal that handed Havoline lubricants to Chevron-Texaco than in his unwillingness to answer your questions. I have found the folks at Shell Lubricants more than willing to answer any and all questions I've thrown at them. A couple of examples: When Rotella T Synthetic first hit the market I asked if it was PAO based or used Shell's proprietary XHVI base oil, which is Group III. I was told that it used XHVI, and I subsequently confirmed this by looking at the MSDS. I also asked about Shell's PCMO synthetic, "Formula Shell." I was told that was all Group III, but NOT XHVI. I asked about Shell Helix Ultra, which I figured the guy wouldn't even know about since it's produced in Europe, but not only did he know about it, he said it was imported to the US only in drum lots especially for Ferrari dealers and specialty shops that service Ferraris.
Try getting answers like these from the Mobil 1 or Castrol tech people.