I'll keep this going since I would also like the answer. Reading on other forums, it appears the popular material is silicone lubricant; a few recommend a dry lubricant. As for 30 weight, I visualize that dripping right to the bottom of the unit instead of retaining to the actual posts where the lube is really needed.
Trailer: Lifted 228BH, heavy duty springs and Yokohama tires
TV: 2016 GMC Sierra Z71 4x4 CC, SLT
Spare TV: Two Alaskan Malamutes
Living somewhere in ID; previously lived in Moab UT; previous to that, don't ask!