I've tried many stuff on Rubbers, the best stuff was a cocktail of just about every solvent i could fins in my garage. The stuff turned milky white with some waterbased solvent, and it smelled awfully. Something between LRP Cleaner and sour milk.. And not even close to odorlees which is required around here
The best odorless additive looks to be Paragon Traction Action, with the new LRP Carpet (light blue bottle) close behind. Many around here uses CS Highgrip too.