I live in the Mojave desert and have recommended this before for rod end bearings but also use it on my slider rails: LPS-1 Rosie
I would give this a try. One brand is called "White Lightening" and is, in fact sold at bike shops. It's designed to be used in lieu of grease on chains b/c water will not wash it away. I would guess that it probably does have some silicon in it but unless you're going to paint your slider track, I don't see why that would be a problem.the dry lube from bike shop.