Looks like Yamaha has reformulated Yamalube 4M. Not sure if there is a significant benefit over the old.

http://www.yamaha-motor.com/outboard/yamalube.aspx
http://www.yamaha-motor.com/outboard/New%20Prod%20Yamalube_4_30C-FINAK%201K%20VERSION.pdf

Both are still available but my guess is the old will be phased out with the new and slightly higher price:
http://www.defender.com/product.jsp?path=-1|311|296536|314203&id=163039
http://www.defender.com/product.jsp?path=-1|311|296536|314203&id=1053686