Yes you can use sandpaper to clean the oxidation, if you don't mind smoothing out the surface of the spokes instead of trying to leave the machined finish on the face of the spokes. I did it on a set of Pontiac snowflakes, turned out very nice. Start with 150-200 grit to sand it down until the surface starts to get smooth and finish up with 350-400 to polish it up a little. It's time consuming manual labor( I'm sure yours will take just as long as my snowflakes did, lots of spokes) but they'll look good. Trying to keep the machined finish and getting rid of the oxidation(pits) without actually removing some aluminum is impossible so you might as well polish them up. And after you're done with the sandpaper get some Mothers Aluminum polish and a buffing wheel for a drill and go to town.