Is Your clutch slipping a lot while cutting?
As
@buzz sawyer said, the sprocket bearing doesn't really turn 13k once the clutch engages.
Maybe You are over lubing the bearing and the excessive lube ends up in the clutch's friction surface causing/allowing slip?!
I give the bearing a drop of bar lube (mineral oil, NOT BIO!) and there always seem to be some left upon the next inspection/cleaning.
Alternatively You could try some MoS2 lube, although honestly I never tried it as I never felt the need for it and just use a drop of mineral oil.
I think something is not a 100% right if Your saws sprocket bearing gets dry all the time!
I can't comment on other saws, but Your DCS6421 sprocket bearing should NOT dry out after only 2 hours of work - that is about 4 tanks of fuel only, right?!
I keep the oil pumps maxed out on my big saws (the little ones have unlimited pumps so maxing out is pointless
), yet I have never noticed bar oil reaching the sprocket bearing!
It actually seems physically impossible as the centrifugal force of 13k rpms drives any excessive oil outward into the drums friction area.
Just saying.
Pictures of what You deem a dry bearing could help.
Like given for a great saw.
Cheers