This is not a "what brand" question but what weight question. I'm riding in the warmer climates so thinker oil seems more logical. For my 250's and my 310 I run 20w50 and so far so good. All the parts look good and clean. However it seams that my '12 wr450 isn't turning near the rpms as my smaller bikes do. I'm not wondering if it might be better to go to 10w40 or 15w oil instead. What weight oil are you guys using?