Typical dealer BS imo. On my 2007 CVO I had a lifter fail and grenade the 110" motor. Tech and service manager blamed it on Mobil 1 V-Twin 20w 50 oil I was using. Said they'd seen several motor problems and common denominator was the Mobil 1. BS because while I didn't know it at the time (and perhaps they did not also) early lifter and cam bearing failure was rampant on the 110" motor and to a lesser extent on the 103" motor which I know because it happened twice on my 2012 CVO with the 110" motor and I had quit using the Mobile 1 'just in case' but that didn't stop the problem.
Fortunately I had no problem with H-D ESP honoring the warranty as this just came up as an aside while we were inspecting the damage to the motor.
So imo forget what a dealer may say and use any oil you want as long as it meets current specs.