Rudder lubrication

Just joined - we have a Freedom 38 (I’m told its the same as an F36, but with added stern platform), we’re in our third season.

Much appreciation in advance for response/advice.

I posted a photo of what appears to be a rudder lubrication fitting on the rudder sleeve on my F36/38. However, I can’t find any mention in the manual about this, and I thought the rudder was lubricated by the water.

Is anyone familiar with this? If so, what is the maintenance schedule, and what grease gun and grease is appropriate?