I recently THRASHED through all the thousands of posts on this forum and other Harley related forums and came to these conclusions: (my opinion only!!)
1) Use oils and gear lubes manufactured for motorcycle (V-Twin) use only.
2) Stick with a well known (positive feedback) manufacturer. I narrowed this to Mobil 1, Redline, and Amsoil for my Harley.
3) Change your fluids as often as possible. If you think about it, this is a REAL CHEAP wasy to maintain good engine health! I plan to change crankcase every 3K miles and the primary and tranny every 5K.
4) My final conclusion (MOST IMPORTANT) was that EVERYONE has an opinion on oils and it does no good to argue with them. Do a little investigation, then just go with your gut feel...it will be right no matter what anyone else says!!!
After all my research, I currently have the following fluids in my Harley:
* Crankcase - Mobile 1 V-Twin 20W50
* Primary - Redline MTL
* Transmission - Amsoil Severe? 75W90
Not sure where I will be for the next round of changes.....