I have used Lucas Red-n-Tacky synthetic high speed wheel bearing grease for a long time now, the tube lasts a lifetime.   I have  9 dynamotors and a bunch of spares I keep running on my milsurp stuff.  The lube schedule in the manuals can be interesting, in the BC375, it says to add 3 drops of SAE20 oil to each bearing, and then a remove armature, clean out the old grease and renew interval.

Charlie