The only cleaner that goes on the scope lens is lens cleaner. Most I see are sprays that clean the glass of binoculars, scopes and range finders.

You can get a scope-bottom cover that's sold by T/C. I only clean the black parts of scopes with a three-in-one oil like Breakfree CLP or Ballistol using a cleaning/swabbing patch. Plus, I always make sure my scopes have lense covers to help keep the glass protected.