I have a Chevy 2500HD with the 2.5" reciever and 2" reducer sleeve. I left the reducer in over the winter and some rust formed where the bottom of the reducer and the reciever meet. I had to knock the...
Although it ain't pretty, nothing beats good ole, cheap, axle grease. I coat every nut, bolt, and seam on my boat trailer with axle grease once a year. It gets soaked in salt water all the time. After 6 years every single nut and bolt looks brand new underneath that nasty looking grease.