Weak Interaction and Strangeness transformation

Is there any processes involving weak interaction that preserve the strangeness for $S \neq 0$?

I can't find an answer to it on net or anywhere else, generally it is true that weak interaction changes strangeness by 1 unit.

Answer

Sure, your PDG reminds you of the strangeness-conserving decays of $$ \Sigma^\pm \to \Lambda e^\pm \nu , $$ where the antineutrino is meant to accompany the electron, mutatis mutandis.

That is, either uus or dds decays to uds , with a very small branching ratio, since, as you are implying, the heavier s is much more likely to decay to a light quark. But, in these highly informative/insightful cases, it is a light quark that weak transmutes to its isopartner.

So it is not true that weak interactions need change strangeness.