Hey man
You might go to these links..
On the Nightrider link there are 4 sections to read..
On the other is perhaps the best info I have ever read about oil..
Have a ball
Motor Oil http://www.sportster.org/tech/Oiland...Motorcycle.pdf
The words here are very small so press the ctrl button and turn the wheel on your mouse forward,, it'll enlarge the text..
Jeeeeze, I wish that worked for everything..!!