I already did a search, and sorry to start another oil thread. My Yamaha dealer stocks this oil and with Red Cap no longer available, I was looking to switch from Yamalube 4 in my 04 450 to a full synthetic. I considered AMSOil, RedLine, etc. but this is the most easily accessible oil for me, or the Redline 10w40. Which is better? I know, I know, been asked before, etc. The Silkolene seems to be pretty popular in the DRZs but not as much for the Yamahas. I guess I am just looking for validation from someone who uses this in their 450. Also wondering if the 15W50 is a good weight to be running here in Dallas, TX or if it a 10W40 would be better.