The best dashboard treatment is NO dashboard treatment. No seriously, all you need to clean your dash is a soft brush, vacuum the vents and groves to get rid of dust and dirt, and then wipe with a clean damp microfiber towel.
Most dash treatments are silicone based, and that nasty stuff just does not go away. Even if you think you've cleaned your dash thoroughly, traces of that still remains. Unless you spend allot of time in the sun, you don't really need any dressing for the dash. However if you do need UV protection, then the only product that will work is 303 Aerospace Protectant. It does not contain silicone and it leaves a matte UV protected finish. You can even use it on the door rubbers and seals.