If you have used a silicon-based product in the last year, I would try to clean it off first. Any wild organic solvent will work for that.

The "oily products" come off by themselves (which is their problem, of course). If you put any of them on recently, then maybe it would be worth removing prior to refinishing. Brakekleen sounds like it would be way too harsh!

Otherwise, just wash normally & dry thoroughly. Be mindful of the Torx-head cladding screws - use compressed air to get the water out of them. Water seemed to make the product go on somewhat unevenly.