There's a whole world of ranges to be found in lapping compounds other than the coarse and fine valve grinding stuff at the auto parts places.
OP, you don't indicate what grit number you're after. Although the stuff from Lee Valley will likely do what you're after. Note that you can also mix it with grease if you want a stickier mixture.
It won't be aluminium oxide (white) though. I seem to recall it was all the black silicon dioxide stuff. If you need the AlO stuff for a particular reason you may need to look further.