Capo used to swear by Amsoil for his S4R.
I'm not exactly sure where he got his recommendation from but you can bet it was a technically competent source. I think there was an American guy, possibly called George, with lifelong experience in oil chemistry who used to post on one of the American ducati forums.
Me, I'm less fussy and stick with Shell Advance Ultra for my 750, but that's partly because I know its compatible with the wet clutch on my bike.
In any case, I like to pick an oil and stick with it for the long haul rather than chop and change at every oil change, my reasoning being that although modern oils of different brands are claimed to mix happily I feel that they must be better off if they don't have to.
This might be particularly relevant for bikes with an oil cooler because unless you go to the trouble of draining the cooler there will always be a decent amount of the old oil retained therein.
Capo of course always drained his oil cooler but I confess that I usually can't be arsed. Well to be fair, its also because my maintenance strategy nods toward not disturbing certain stuff (like oil cooler hoses with seals, or rubber mountings) unless you have to. But then again, I seldom run oil to anything like its maximum lifespan so even the old oil from the cooler is still likely to be decent. And I know it'll mix perfectly.
I'm kinda boring in my oil choices .... but not without good reason.
The mainstream, recommended choice is a safe choice that covers all the basics.
Its probably not the most expensive, so you can afford regular changes.
Its also easily obtainable and likely to remain so.
Also by sticking to one choice, there's no waste bits left over and easier storage too.
You'll probably not be surprised to hear that I have two bikes and I run them both on Shell Advance Ultra .. though again they both have wet clutches which this oil suits.
As a general rule, I'm happier with an oil produced by a big name manufacturer who has the financial clout to do extensive R & D, rather than a niche, little known brand.
For that reason I would naturally tend to steer clear of something called Royal Purple.
Though I heard that they recently changed their name and now insist on being called "The Lubricants formerly known as Royal Purple".
