Its not a good ole Yami and this is a 2 stroke but I just sold a 2001 cr250r that I ran Mobil 1 in and I changed it after every ride. It was 5w 30. The reason I used it is because it is a really good oil and I also got it free from work. My tranny shifted alot smoother than using HP2. It didnt effect the clutch at all. The only reason I changed it after every ride is because it was such a light weight and I had a bunch of it. Just my $.02 .