Most anything that will introduce carbon into the melt is used as flux. A whole bunch of guys use saw dust. Toss a half handful on the melt, wait 'till it's charrred and stir vigorously into the melt, scraping the sides and bottom of the pot. Most of the gunk will come to the surface to be skimmed off. At least that's what I do...
The only thing I lube on my alum. molds is the mating/locating "pins". A very light drop of Bullplate works wonders. (BTW, nothing goes in the cavities of any of my alum. molds, no "conditioner", no "release", nuttin'). Occationally I'll put a VERY thin dab on the underside of the sprue plate. Good stuff.