with a dino oil, my bike felt sluggish, but here is the crazy thing, the sound out of the pipes was deeper, almost a better sound. I had a friend riding beside me at about 50 and he said the pipes sounded pretty good since he knew I always complained about them. With synthetic, the bike felt it flowed better. Like nothing was holding the engine back. Almost to free like it was running on air. Te pipes had that raspy tingling sound, no deepness. I know this sounds crazy but you asked. All Dino were 10-40, GN4 and regular Spectro. With the synthetic blend of Spectro is was almost in between the 2 stages I just described. On first cranking up when cold, it would hold a idle better with the blend and dino, then with the synthetic, go figure. It runs faster, accelerates quicker with the synthetic, but the engine at high revs almost sounds whiny, but good. Also, as I told my dealer, he was still selling the regular Amsoil that says it can be used with bikes. I told him that Amsoil has a motorcycle specific oil now that from what I understand has zinc where as the other didnt. So with synthetic, it runs better, cooler, no fan at all even with 2 up, but the bike sounded better with the blend and the dino. So there, I showed you mine. :shock: