Just been to Costco and they have started selling Castrol Edge 0w30 engine oil for £32.50 for a 4 litre bottle.
Spotted this after spending £2 a bottle more at Eurocarparts, bugger.
That's only in Liverpool I believe. By premium do you mean normal unleaded or super unleaded? If just normal unleaded my local shell is 128.9 anyways and after my little trip it didn't get much more expensive than that at other Shells I stopped at down south at 130.9