They aren't enduring very high rpms compared to what they are rated. The centrifical force only
puts the oil into the outer race as the balls roll through it, so not much lube needs to be added, like once a month...
The abec5 ceramic bearings I used are straight skate bearings and are really overkill for a tattoo machine as the rpms arent very high, but they are lighter and about 10X longer lasting than steel. Maybe less resistance for the motor too? Plus they look cool all white. Because they are skate sized bearings they are made in higher numbers than other ceramics so the price isn't too bad at all if you shop around. I got an 8pack for about $40