Iâ€™ve got a â€™05 red and black. Around 4200 miles my engine started to get this rattling noise on startup. Almost sounded like a diesel engine when it was cold. As the engine warmed up the noise slowly went away. It always ran well but the startup noise did not sound good. I did some searching on the site and found a couple of posts that described similar symptoms and nobody seemed to be too concerned so I did not freak out about it. Last week I switched to AMSOIL 10x40 synthetic(I was planning to do this anyway) It did not seem to make any difference with the noise, however, today I go out and start my bike and the startup rattle is there. After about 10 seconds of run time the rattle just stops and does not come back. My question is, do any of you think that running the AMSOIL was what quieted the engine or just a strange coincidence??