I put metal valve caps on my tires a year or so ago, because I'm an idiot. When I went to add some air to my tires one day, I found that the caps were seized up. Now I am unable to get them off. This is a sensitive part, so I can't just muscle them off.
I have tried:
Liquid wrench.
Holding the stem with pliers and turning the cap with another pair of pliers. I used as much pressure as I was comfortable with and no joy.
I'm out of ideas, because brute force methods will lead to much bigger problems.
Any ideas of how I can get these off without causing further damage?
Edit:
These are rubber stems, and luckily they don't have a pressure sensor (i hear that makes them extra fragile)
now I know why valve caps are plastic