[CORattler]

Hope this helps:

From the Lippert 5TH WHEEL HYDRAULIC SLIDEOUT AND LANDING GEAR (HLG) SYSTEM MECHANICAL SYSTEM MAINTENANCE OPERATION AND SERVICE MANUAL

Although the system is designed to be almost maintenance free, actuate the slideouts and jacks once or twice a month to keep the seals and internal moving parts lubricated. Check for any visible signs of external damage or “leakage” before and after movement of the unit. When the room is out, visually inspect the Inner and Outer Assemblies of the slideout. Refer to Fig. 1 for location of inner assemblies. Also inspect around
the shoe of the leveling jacks for signs of leakage. Check for excess build-up of dirt or other foreign material; remove any debris that may be present. If the system squeaks or makes any noises it is permissible to apply a coat of lightweight oil to the drive shaft and roller areas of the slideout only but remove
any excess oil so dirt and debris do not build-up. DO NOT USE GREASE.
NOTE: For long-term storage: It is recommend that the room be closed (retracted).