Let me throw some kerosene on the fire here. In 04, I bought a '99 RK with 20K on it. Added an AC, Fulsac pipes, VH mufflers and SE Cams (don't remember the grind). It ran good. Ran 20/50 HD oil. When I sold it with 50K on it, valve train was making a ton of noise. Bought an '08 UC new. Customized the sh!t out of it, 103" kit, AC, SERT, Andrews cams, Klock Werks Wrap Around duals with Monster Ovals. The exhaust cost me a bit in HP, but my numbers were 101/108. She was a tad noisy and ran hot. Switched from Syn3 to Amsoil 20/50. Noise and heat were immediately down, and mileage went up almost 2 per gallon. Two other UC's, one built and tuned by the same builder as mine and one with just pipes and a tune. Both switched to Amsoil and experienced the same reduction in heat and noise. I ran that bike for 8 years, and over 50k. Got right around 40-42 MPG. Now I have a BRAND new 2016 CVO RGU. Already have a set of V&H Monster Ovals, American Custom True Duals, and the stock 110 w/SE air cleaner. Added a V&H Fuel pack for a tune. It's due for its 1K service in a week or two. I will not only run the Amsoil 20/50, but am putting their new primary case oil in the case. I also ran Redline's tranny oil on all three. I have NEVER had a motor issue, a leak issue, or even a burned oil issue. I change it at 5K religiously. I swear by Amsoil!