My bike is a 2006. When I purchased it new Triumph was using Mobil 1 Full Syn 4T 15W50 that was made in Europe. Triumph recommended using the Mobile 1 15W50 as the most preferred oil. When Triumph and Mobil had a falling out, Triumph then switched to Castrol and recommended as the preferred oil the Castrol Full Syn 4T 10W50. I've been using both of these oils since new with annual or 5K mile changes and so far 40K miles later all is still good.
Changing the oil at the first 500 miles is very good. It is done to remove the metal bits that are ground off during break in. Doing it again at 1000 miles is OK too. Just a little more protection for the transmission. You see, the old school mechanics, especially in heavy equipment such as 18 wheeler type trucks, will tell you that anytime you install new or rebuilt engines, trans or rears ends, you should change the lube at 1000 miles. This removes all the metal bits from break in and prolongs the life of the unit. I still work on the old school methods. My stuff runs and runs and runs with very little trouble. I say the old school methods really work and are definitely worth the time and expense.