Sorry to say, but the posts here are right. Never use grease on the moving parts in the camper (except for the axles of course).
It attracts and retains dirt and road junk. It will reduce the service life of your slide mechanism components. Always use the correct DRY lubricant. It is powdered graphite in spray can. The carrier agent evaporates quickly leaving the dry powder behind.
Improper maintenance of the slide seals can cause the seals not to flop out when the slide opens. Never use silicon spray or "armor all" on those seals. Use the correct "slide seal" lubricant. If the seal is "too slippery" it will just slide along with the slide and not grip enough to flop out, or in, with the slide's motion.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW