Oil, zinc, synthetic, weight

I was looking at Amsoil synthetic for my car and noticed that their "extra zinc" formulation is JASO-MA rated and their label mentions that it is suitable for motorcycles with wet clutches. I think it was 20w50 and it cost $10.99. Right next to it was there motorcycle oil and it was $11.99. So I got interested in the pros and cons of extra zinc and found these two articles. I like synthetic and have never had a problem so I will continue to use it, either Amsoil or Mobil 1 but probably will not worry about the extra zinc since I just cruise around and highway speeds. At 71 I'm just getting a little too old to take too many chances--been there done that when I was younger.

http://www.theyeagergroup.com/oil_bible_motorcycle.pdf

http://www.drivenracingoil.com/news/dro/training-center/articles/zinc-in-motor-oil/