Brian, thought you might have bought some 4L cans with your XS-550 from Barnet. It only cost us £18.50 per can so we bought 18 of them!! Thats probably not the best price in the UK but it was very convenient for us and a hell of a lot better than Irish prices.
Scotty, the only problem with getting Opti oil from the UK is that it generally ships as hazardous goods and can work out quite expensive once shipped over.
If In Doubt, Go Flat Out!!