Alf and I discussed this earlier in a discussion of squeaky Andersen hitches
I checked the instructions for the Reese 16K Fifth Wheel
, and this is what it says about lubrication each trip:
1. Lubricate skid plate surface of the hitch (see figure on cover of Manual) with automotive type chassis grease or use a plastic lube plate to provide a lubricated surface. Use engine oil to lubricate pivot points of moving parts within the hitch.
2. Plastic lube plates (Reese No. 74295) can be used to avoid messy grease. The plastic lube plate must not exceed 3/16 of an inch in thickness to ensure hitch will operate properly. Lube plates must be 10 inches in diameter or larger to properly distribute king pin weight.
I didn't find any reference to greasing the pin or jaw surfaces, so I guess it isn't needed.