On my DR350SE I have only 2300 miles on it and the bottom of the engine seeped oil after every ride on HP4 which was in for about 500 miles. I changed oil and this time used Chrevron Delo 400 15w40 (less than $2 qt). Guess what? No more seepage period! On Chevron's website they recommend Delo 400 in motorcycles as does Shell recommend their Rotella 15w40 and synthetic 5w40 for motorcycles on their website. For those who havn't checked out the diesel oils, they have all the zinc and phosphorous plus less polymers which are bad on diesels. While I'm still breaking in my XR650R on the Honda oil I think I will be using the Shell Rotella synthetic 5w40 or atleast the Delo 15w40. I'm not too worried about spending more on the motorcyle oil but no I'm starting to think why bother with these heavy duty oils out there? http://www.rotella.com/qa/answerresult.php?rowid=81 from Chevron Q&A "My motorcycle owner's manual recommends against using an SJ passenger car motor oil. What product does Chevron have for my motorcycle? Due to the inclusion of fuel economy requirements in the API category SJ, many oils have been formulated to contain friction modifiers. In a motorcycle wet-clutch application, these additives cause clutch slip and power loss. Chevron Delo® 400 Multigrade SAE 15W-40 is our recommendation for motorcycle use. "