Which bike are you talking about?
The x,o,z ring keep the grit and moisture out of the real area of vulnerability, the enclosed & greased link shaft. Given the fact that you're already experiencing some tightness, and by that I mean a/some link(s) that won't extend out, I'd say that replacing chain and sprockets are in order.
You could continue; it won't break, but it's going to eat up a lot of other more expensive parts. And make a hell of a lot of racket.