Nevr Dull is great stuff. However, I got a most unexpected result from using it on the bumper of a car I was rebuilding years ago. It seems the fellow who was helping me rebuild the engine had extensive experience with it in the Navy, like Hardcase, but he didn't appreciate it as much.
When he saw what I was using he launched into an invective much like his legendary sailing predecessors are famous for. A summary of his 10 minute rant is that, as corrective action for some imagined (he claimed) transgression, he had been suggested to a flag officer as the perfect seaman to polish everything that shined, or was supposed to shine, on an aircraft carrier while it wandered about the seas of Southeast Asia for long periods of time. He had hoped to never see another fiber of Nevr Dull for the rest of his days.