Well I am a complete 4-stroke noob, and I just got a 1999 yz400f. The bike is great and the previous owner changed the oil right before I bought it from him. Since I bought it I have ridden the bike maybe 6 or 7 hours, and now I need to change the oil. The previous owner said that I should run Yamalube 4R. Should I? Or what is everyones opinion on what is the best oil for my bike? Thanks.