rearend fluid level question

ok, so the axle bearings are sealed and that will be enough to handle the lubrication. I am used to doing semi's where they are oiled with rearend oil. That make sense. Reason I asked and found a problem is that I had an oil leak back on the inside of the rear wheel. That is why I pulled the axles out to replace the gaskets. I noticed that the bearings were really worn. fluid level couldn't be touched with the finger in the plug hole. I just assumed that the axle bearings were oiled from the housing like on a semi. excue the brain fart. First time for replacing axle bearings. learned something new today.Thanks