Angry Pirate...if you read the Amsoil document, it is comaparing HD Syn3, NOT the "Old" Screamin' Eagle oil. Nowhere in my ESP does it state that I must use HD products, or get my bike serviced by a HD dealership. The HD 2 year warranty does not specify that either. If you purchase a HD Service Plan, they put HD products in your bike. Syn 3 does not have a "magic ingrediant" making it superior to other synthetic oil. In the crankcase, you could use any 20W50 motor oil, including synthetics...synthetics are more resistant to high temperatures, so IMO, they are a better choice. In the primary, you need to use a motor oil designed for use with a wet clutch...or you can use Automatic Transmission Fluid, as some people do. My HD dealer actually recommendsusing Redline Shockproof in the transmission, as it is their experience that it performs better than running regular motor oil, including Syn 3.
The bottom line is that NO vehicle manufacturer can specify which products to use when servicing your vehicle, as long as it meets the specifications required. If they do specify, they are legally required to provide the product free of charge.
It really isn't necessary to change oil every 2500 miles either. That is a holdover from back when motor oil was not what it is today. It doesn't HURT anything to do so, of course, but it is just wasting product. The only time it might be necessary to change more frequently than 5K is if you ride on dirt roads, stop and go traffic the majority of the time, or travel very short distances the majority of the time (the motor oil never gets up to operating temps).