Anyone have succes with Royal Purple 10/40 ? I have a chance to pick it up for $1 a qt less than Mobil 1. So far,I've had good luck with Syntec & Mobil 1 synthetic until 100 miles after oil change.Then shifting gets progressivly worse(notchy). This is on 02 B12. My GS 1100 doesn't have this problem,although both bikes like synthetic better than regular or synthetic blended url.