I will disagree with the Honda-moly recommendation. I have a tube and used it on my 1st spline lube.
When after a couple of months the downshifting became more difficult. When I tore into it again all the Honda Moly was slung off.
Upon looking around I found the recommendation for a product called Guard Dog Moly. I used it on my second go around and I'm very pleased. Probably a year or so later and still shifting like butter.
Compared to the HM, the GD is really tacky and super slick. It's kind of hard to find, but it's worth finding, IMHO.http://guarddogmoly.com/prod-moto.shtml
That fellow Paul Glaves in the picture on their website is kinda of a K-bike guru.