So how do I take care of W-D40?

Hint 1 of 11:

First, I'd suggest looking around the area to see what resources you have.

Hint 2 of 11:

Did you notice a boulder on the screen with the gap in the path?

Hint 3 of 11:

It would be nice if you could crush W-D40 under that boulder.

Hint 4 of 11:

If you notice, W-D40 will follow you just about everywhere you go.

Hint 5 of 11:

And you should notice that the boulder would roll into the cave to the left
of that gap if you pushed it.

Hint 6 of 11:

If you're quick enough, that's where W-D40 will be when you push the boulder.

Hint 7 of 11:

Now all you need to do is find something to free it.

Hint 8 of 11:

There's really very little here.  You may have to go out on a limb to do
anything.

Hint 9 of 11:

Well, I mean that literally.  Take a look at the tree on the screen with the
giant log.

Hint 10 of 11:

Try walking on the tree to see what happens.