Not@home wrote:
I have a metal link screen suspended by metal rings from a steel rod
right in the front of my fireplace opening. Over the years, it has
become harder and harder to open and close the screen, although I
can't see any rust. If this wasn't a working fireplace, I would just
lubricate it, but most of the lubricants I have are shown as very
flammable on the label. The only exception is some ancient high
temperature grease that is so old there are no warnings on the label,
not even about causing cancer in California.

Should is risk it? It wouldn't actually be in contact with the
flames, but about a foot away. Or is there some other lubricant that
would be better suited? Hate to burn down my house experimenting.

Try a few drops of motor oil. The temperature inside your engine's cylinder
has got to be hotter than a fireplace.