Oiler (?) wirth HF Micro die grinder

I recently bought a "Micro die grinder" from HF:

For $9.99, what the hell! I just used it and it's really nice for delicate work, where its super light weight makes it very easy to handle.

But, the purpose of this post is to ask about the oiler that came with it:

least, I assume that it's an oiler. I put oil in it and the oil went into the grinder. Boy, did it ever - into & out of and all over my hands! So what's the trick to using these things? Do they have to be oriented a certain way? The included instructions did not even mention the device.

Thanks, Bob