Good day, just bought a royal star venture 2000, i was not used to the engine noise, so i was recommend to put semi- synthetic oil 20-50, which did improve noise level below ~ 90 km / h. The bike has only 33 K km, and as per reading the note - noise may go lower in time. Any word of advice? The shop used Belray semi synthetic 20- 50 for the engine. Thank you.