What should I use, if anything, to preserve these steps made of treated wood? These are on my townhome's back porch. Two of the steps are directly exposed to weather. They were filthy but cleaned up fine with Murphy's Oil Soap and some scrubbing. Should I preserve them with something or just leave them alone?
It basically depends on how long the steps have been there for one. You can stain fresh new pressure treated wood, but if its still wet, it doesn't take well. If it has been seasoned and is dry, as it looks like it is, you can stain it.
They make stain, for pressure treated wood even, which helps prolong it. Between that and keeping water from pooling on it, it should last quite a while.