I'm another supporter of kerosene or #2 diesel. I'll tend towards diesel in the summer, kerosene in the winter, because I let this sort of stuff sit in the unheated part of my shop.
Acetone strips oils. It sure does a nice job removing oily gunk, but when you're done and you go to move the slide, you'll have metal-on-metal contact very quickly, with no lube, if the acetone has done it's job well.
Kroil is another very good penetrating lube.