I was actually using WD-40, but it definitely seemed the stone was getting clogged. I used the included eraser a few times, but it still took a long while. I'm using the veritas mk2 honing guide.
MK2 is a good one for consistency. DMT recommends spritzing with water periodically (not oils, etc) so that the swarf floats and doesn't clog the stone (you can see the swarf). I give them a quick rinse in the utility sink every now and then and then back to sharpening. When done, a final rinse and a light scrubbing with an old tooth brush, rinse again, and a final rinse with DNA. Never had a rusting problem on the stones or the tools