Good old Vaseline! It will penetrate, clean, restore, and preserve the old finish, & color back to like new. Just apply (I use my bare hand), let DRY (in the heat, or sun), then wipe off the excess, with the dirt, & grime. It may take a few coats, & some time, but you'll be amazed! No rubbing, no polishing needed. Once fully restored, & Dry, you can just leave it, (it lasts a few yrs), or wax, or polish over it with whatever you want to preserve it even further!