Chip oil splattered up the back of the range on the splashback.
"Someone" didn't bother to clean it off and it semi-solidified....
Brake cleaner, Mr Muscle, and other kitchen cleaner stuff just didn't shift it but....
Colgate did !
Absolutely sparkling shine and so clean you could eat your dinner off of it. Drop of water on a simple nylon brush and toothpaste cleared the lot.
And it smells better too ;-)