Can I lube my yoyo without taking the c clip and the shields off?
In case that I have to do it, do I have to put back the c clips and shields or just leave them off?
You don’t have to take them off. And you can leave them off if you take them off.
It’s easier to clean and lube them with the shields off. You don’t have to put them back on but it’s not hard to do.
Once again, I refer you to this topic for a plethora of yoyo knowledge, hints and kinks…
Useful modification & maintenance guides - Axles,Clean, repair, tune, fix yoyos
Funny, I just logged on to ask about the shields too.
What kind of lube do you use? (Just wondering)
you don’t have to take the C clips off to lube it. 8)
hope this helps 
But it makes it a whole lot easier and more effective. If you don’t most of the oil sits on the shield rather than going into the bearing.
I don’t take the C clips off when I lube my bearing. it works just fine.
You don’t need to take shields off to lube a bearing.