Southy, after the Castrol "synthetic" ripoff, I stopped using their products. Recently they were bought by BP. At work, if I approach the castrol sales representative for an alternate product, I get a reply call from the BP Technicians (which is the product that I want to replace).
If they stopped lying about synthetics, and kept themselves "aloof", as in technically superior to their owners, rather than just an elitist brandname, I'd be buying their products still.
As to Valvoline, they are lacking in additive packages (although if you add one of their additives - why would an oil company market an oil additive ?), you get a decent oil.....for more than the price of a decent oil.