Turntable

Miguel, I think the same cautionary notes apply.  In this case, you'd want to know that the sealer does not interact with the actual lubricant in a bad way.  Anyway, for a turntable bearing, I would also wonder why sealing the pores in the metal parts is critically important; the parts in the bearing bear forces across their contact surfaces.  Do the pores, such as they may be, enter into this?  I dunno.

@lewm 

That makes perfect sense to me.

No.

I recall the Microlon product many years back, a similar 
metal treatment product that filled metal pores, a friend
applied it to a micro piston engine and found the RPM increased
quite noticeably indicating naturally less friction.

Would I apply a similar product to my TT bearing no. 

I agree the most here that for a TT bearing, a separate product that needs to be applied prior to and in addition to the bearing lubricant is not necessary.

I would concur that products such as Caig that are meant to be applied on electrical conductors that fill in microscopic gaps, do work and are beneficial in that area.