Fifth wheel trailer mechanisms are subjected to a great deal of sliding and shock loading. Typically, fifth wheel surfaces should be coated with NLGI #2 grease before connecting the trailer. Since the existing grease on the surface has probably already collected dirt and other contamination, it should be cleaned before applying new grease.
Some fifth wheel mechanisms also contain a rack and pinion gear for positioning the trailer. These components often require special greases containing solids such as molybdenum disulphide or graphite so that the contact surfaces continue to be lubricated when the grease is squeezed out. For most applications, we recommend Mobil Delvac™ Xtreme Grease 222 Special. It is a NLGI #2 lithium complex grease, designed specifically for use in severe on-road, heavy-duty trucking. It is particularly effective in rust protection. It also has sealing and tacky consistency in dry conditions, and its high-water resistance capabilities help reduce lubricant consumption and increase bearing protection in wet environments. Most important, it offers very good rust and corrosion protection to help provide long life to bearings and chassis lube points.