In another thread, someone who claimed to have bearing industry experience stated the irregularities on cheaper, lumpy bearings can help carry the lube to where it's needed...but grade 10 or smoother balls sometimes had lubrication starvation issues related to their ultrasmooth finish.


If this is true, then the smoother bearings should be lubed with synthetic grease as the synthetic oil it's made from has about four times the film strength of mineral oil.

All in all I would say the viscosity was more important to the larger ball bearing hubs such as the IGH hubs or to coaster brake hubs because you have pads running against a brake surface in a bath of grease and there is a large surface to create drag.