RE: sealing grease?
So little water gets in the nyrods that it is questionable whether if it is worth the effort. A squirt of spray silicone lubricant into the nyrod housing will cause any water intrusion to bead and further impede the flow of additional water. Water comes in through hatch covers and wing saddles. The Nyrods are never immersed, even if the plane is floating on its back.
I had always used saran wrap and silicone sealer to seal wing saddles ( with the saran wrap acting as a parting agent.)
Last time I did it I wet the wing with silicone spray where it would meet the caulk and set the wing into a bead of caulk. I let it sit for a week so the caulk would have time to cure with very little of an air path. It sealed perfectly, and there were none of the wrinkles I had experienced before.
Unlike vaseline or Silicone grease: RTV or caulk form a permanent flexible seal that will not leave a film that will prevent you from being able to repair the covering at some time in the future. If you've ever tried to patch monokote over a slimy place on the plane-it ain't gonna happen.