For my '08 Dyna (15,500mi) Mobil 1 for sure every 2500 (it'll be dirty) and Spectro GL5 for 6 speed for the trans comes highly recommended but I did not find that it was any quieter then Harley brand. Just turned 1000 on my new FLHRC, LOVE IT, can't afford the 1000mile dealer service (fixed income) yet and I don't want to park it, soooo.....thought I'd just do all the fluids myself right now and have the dealer do the rest when I get the $$$. I have heard from an "oldtimer" that Harley's new V-Twins can expect 150,000 mi + with regular service. That's what I'm talking about.