In the sportster the 20-50 is for the primary/trans too. Though you will find folks here that say they've run A,B,C without issue. It's up to you, here's AMSoil's take on the sportster lubricant:

http://www.synthoils.com/harley_davidson_lube.htm

I don't know enough about the sportster clutch to know whether or not the EP friction modifiers cause it to slip or not, but I have never heard of anyone's components failing due to following AMSoils recommendations. This is of course with the exception of failures caused by metal fatigue unrelated to lubricants.

 

[quote=JC Sporty;8600700]Which begs the question, how long do you guys run synthetic oil in your bikes? I would think you could stretch out the intervals over conventional oils thereby covering the added cost. I used to run red line synthetic in my big twin trans and it was a night and day difference in the shifting. Didn't notice much difference in the sporty though.[/quo

about double the milege of reg oil

 

Did you get all that? lots of chatter.
Can someone boil all this down to a meaningful script, hey admin what do we pay you for?

 

MIGHT BE OK TO LEAVE THE FILTER BUT I WOULD CHANGE IT TOO....jmho

 

Synthetic oils have better thermal qualities and resist breaking down much better.Always change the filter unless you want it to get too dirty and have the oil bypass it all together.Doubling the oil change interval?Go ahead they say your okay,if your that much of a cheapskate buy a Honda.That way you would have saved money up front as well.