AmsOil 20/50 Full Syn. In all 3 Holes and I change it every 4k they say your supposed to be able to double your oil life will the AmsOil full syn but I don't trust that in my bikes. I ran Redline 20/60 for awhile (Was supposed to be specially designed for Harleys) but It made my bike run a little on the hot side so I went back to AmsOil, good cooling and my motors have stayed clean. AmsOil full syn. has Lasted me through 3 Harleys and into my Current Road King #4 One of them was a high HP Buell motor in a Sportster Frame. Never had problems. Even worked ell with my Evo Wide Glide with Cork Gaskets.