Seems so far the responses are all for dressings, not cleaners. A dressing won't do you a bit of good if you don't first properly clean and prep the surface. A dressing is fine to maintain going forward, but only AFTER you've got it properly cleaned!
You'll need to first deep clean the rubber and remove the oxidized material and any stubborn dirt. To do this use a quality APC and a microfiber towel to scrub the trim. If you need an APC we sell ours in a concentrate form - at 8:1 its great for this job:
Surf City Garage - Surf City Garage Professional APC Concentrate - Cleaning & Decontamination - Surface Solutions - SCG Professional
After cleaning flush with water or wipe with a damp towel to remove any residues from the cleaner. THEN at that point apply a quality water based trim dressing to restore a nice look and keep it moisturized and protected.
Again here, if you're looking for a solution our Exterior Trim Conditioner is a water based concentrate that can be used right out of the bottle for higher gloss or cut 1:1 or more with water for lower gloss looks. Some of the other options suggested above are good as well if you already have them.
Surf City Garage - Surf City Garage Professional Exterior Trim Conditioner - Trim & Tire Care - Surface Solutions - SCG Professional
