I know there are a few posts out there on this, but I thought an update/revival would be nice.
I recently (October) purchased a travel trailer. During PDI, I asked the tech how to lube the hitch and he waved his hand and said "put some grease here and there". He indicated greasing the friction points on the sway control as well (NO! you shouldn't do that! I already knew at least that part.)
The hitch is a Fastway E2. This hitch has integrated sway control accomplished using L-brackets attached to the tongue of the trailer and round bars that distribute weight and use the friction against the brackets for sway control.
Anyway, so I've been towing with it unlubricated (except for the ball) and finally got tired of listening to it and bothering the neighbors.
So I got some marine grease (because that's what I had from our old boat) and went to work. I put some fresh grease on the hitch ball, and the part of the bars that go into the hitch head. I didn't use a lot, just enough for a nice thin layer, applied with my fingers.
Now here's the cool part: I had read somewhere that if you wanted to quiet down a friction sway WDH, use Vaseline. I thought "seriously, Vaseline?". The answer is YES! I put a good gob of regular old Vaseline on the L-brackets and the bottom of the bars, and WOW! What a difference! Between the grease and the "lube" my entire hitch barely makes a sound now. The Vaseline doesn't add any significant lubrication (at least not enough to overcome the friction of the sway control) but it sure does quiet those bars down! AND it makes them a little easier to pry into place.
Now get out there and lube your stuff! You won't be sorry!