How could it be labelled fully synthetic if it's a group 3? I thought that only in North America they can call group 3 oils as fully synthetic, but over there they must label group 3 oils as semi synthetic.
Keep something in mind: While Helix Ultra does have Shell's XHVI (Group III) as part of the base oil blend, it's just A PART of the blend. There is a substantial amount of PAO (Group IV) and esters (Group V) in there as well. And for the newest Helix Ultra (0w40), there is probably even more Group V than before. Same with the 10w60.
Castrol RS may be of similar make up: some Group III with a lot of Group IV and V as well. I'm pretty sure it's only in the North American market where Castrol has labeled a predominately Group III based oil as "full synthetic."