I use screw on fittings, not the compression types and I put them together using Vaseline Petroleum Jelly at all coax connections. Been doing this since back in June of 2000 when I moved my Winegard dish from the old house to this new one.
IMHO it's just as important to keep air out of those connections as it is to keep water out as 80/90% summer humidity is about as bad as actually being submerged in water. No air or water in those connections = no corrosion problems. And did I mention that Petroleum Jelly is cheap, and, I'd bet you already have some of that in your medicine cabinet!
RE: Signal degradation from using this stuff? Well, I get most all the stuff others pick up so I can't say whether or not there's any problems with it. If I had problems getting stuff I want to watch, then I'd probably try something different but the way it's working now and has worked in the past is good enough for me.
Oh, and did I mention that I like stuff that's cheap?
