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...
Since I carry WD-40 in my truck side door pocket I spray mine with that when it starts looking discolored. I have also spray painted the hitch when needed which also helps.
If I am on the road alot I use the grease supplied by the RV dealer on the BALL.