Honestly, the builder of the slide will give you what type of lube to use, and they are much more likely to be right then a bunch of Internet X-perts who don't even know which model or maker it is.
2008 F350SD V10 with an 2012 Arctic Fox 29-5E When someone tells you to buy the same rig they own, listen, they might be right. When they tell you to buy a different rig then they own, really pay attention, they probably know something you don't.
Lippert Slideout Componants is one of the biggest slideout manufacturers, and they say not to grease or lube the slideout Mechanism. Tests show that after thousands on in-out test cycles the slideouts still operate properly without lubricants.
Keep it clean using soap and water, and if it should become balky or noisy use a dry lube such as Rem-Oil Dry Teflon or Slip Plate Dry Graphite spray.
The #1 cause of issues with slideouts, per Lippert is the mechanism becoming clogged with road debris sticking to the grease. #2 most common issue is loose, dirty or corroded electrical terminals.
My posts shouldn't be taken for factual data. They are purely fictional, for entertainment purposes and should not be constituted as actually related to scientific, technical, engineering, legal, spiritual or practical advice. Amen.