I have been using the SMF-103 on my Speedmaster since the bike was new in April of 2003. I have been a dealer/user since about 1979 and have had nothing but excellent performance from all of the products. The product line has grown immensely over the years and everything still seems to be top notch. I have been running the 10-40 but up here in Alberta we don't get to many extemely hot days so I think I will continue to use this weight of oil.
