I bought my R1100S used from a local guy and he showed me the liter jug of the 17 dollar a liter boxer oil from Europe which he recommended. I went to the local shop and bit the bullet for my first oil change. But I really wonder what magic fairy dust this synthetic liquid gold has at 15/50 that the Mobil 1 5/30 that I run in my turbo charged WRX boxer that has been run hard and now has 150k on it does not have. I get the Mobil 1 6 pack for the price of 2 liters of the boxer oil from Europe. Is the difference that I need the 15/50 because it also runs the gearbox. Thanks from the clueless.