I have used HD Sportrans and now that it is discontinued I am using HD
Formula+. I see absolutely no reason to experiment and drive myself
crazy. HD branded oils are very good quality and are tested with the
bikes we ride. Are they the ABSOLUTE best? Probably not, but who
cares?! They are good enough and make my life simpler in the
motorcycle maintenance department. I have an HD dealer nearby and
close to the only thing I buy there is oil (I have a permanent engine
oil filter). If the dealer was not convenient then I may start
thinking of alternatives.

Good luck and make sure your brain does not explode before you settle
on a primary case oil. You will need it to drive yourself insane over
the engine oil choices :)

--
Vladimir
'04 tax-paid XL883
Pioneer Valley, MA