Everyone believes there's is the best approach and I guess I'm no different. I use AMSOIL 20/50 in the engine. Why because there is industry data available that says it protects the engines the best. In the Trans I have been using Bel-Ray 85/140, when I complained about how noisy my HD Trans was my dealer recommended BEL-RAY and I haven't had any issues and in the primary I use HD Formula Plus. This combination has served me well. I traded a 1997 Road Kind in with 88,000 miles and my 2007 Street Glide which is now my TRIKE has almost 38,000 miles. I used to use the AMSOIL in all three holes but everything runs kind of noisy. Ride Safe!