[TowerTalk] Above the Thrust Bearing

[Jerry K3BZ]

My old-style Heights aluminum tower has a plate to mount the rotator,
another plate 18" above that for the thrust bearing, and 18" above the
thrust bearing the very top of the tower is a 12" section of aluminum tube
with an ID of slightly more than 2 inches.  The mast would have
metal-to-metal contact as it passes through the tube. Is it necessary and/or
desireable to grease or otherwise lubricate the mast where it passes through
this tube?  If so, what's the best lubricant to use?

Jerry K3BZ