I tried some used motor oil but I didn't care for how it turned out. Number one, it kinda stunk like a mechanic's shop in my basement. Number two, the oil would vaporize in the firebox and flash, which smelled like I burnt down a mechanic's shop in my basement.
Number three, I don't think it helped the dust problem very effectively since I couldn't distribute the oil onto the coal very well. SO, I'll just be gentle with the coal and try to keep the dust down that way. OH, I should also note, Having a baro damper acts like a vacuum cleaner in the sense that it pulls in the dusty air instead of that air proliferating up into my living area