A few years ago I was also researching "Pure" synthetic oils for auto use. I cant remember the site but it had tons of info, I will try and find it again. But I do remember that it stated that you cannot mix a "Pure" synthetic oil with any of the so called "fully" synthetic oils we can find here in the US such as Castrol and Mobil as they are not really "fully" synthetic. To actually use a "Pure" synthetic you would need to completely flush the whole system of the old stuff to get any of the benefits of the "pure" stuff and the stuff ain't cheap. So where are the chemists on the 'Wire' when you need them ?

As far as testing the present synthetics in the US I have also tried most of them and found that my Rodeo burns any of the Mobil stuff faster than any of the Castrol stuff, Castrol 5w-50 seems to do the best for me, even over the Dinos.