Weight of oil is the second number - this is equivalent viscosity at the operating temperature. First number is at 0 deg C, important only if you start it in low temperature, and completely irrelevant for synthetic oils.You see no problem in using a lighter oil then triumph calls for? 5-40?
I've checked data and reviews on Amsoil 10W40, looks like the best you can get. This is my next oil to change to - price basically the same as Mobil 1 Racing 4T. I have a distributor nearby.ive been using mobile 1 as well, but im getting ready to try something new. not sure what ill go with.