I was under the impression that mild detergent and water was the reccomendation for sharkskin lines. Maybe that has changed.
For smooth lines I have found Glide to be the best product, especially if you leave it on overnight and buff it off the next morning.
For cleaning only I have used Lazer Line Speed with pretty good results although it might dry out some lines.
Good luck - I never seem to get more than a season or 2 out of my lines!