ORIGINAL: countilaw
The improper use of the ethylene glycol, (anti freeze) will cause the aluminium to turn dark. Plus it is very expensive.
Actually antifreeze is pretty cheap and the pint or so required can be used a number of times. It will turn aluminum dark if used at too high a temperature and, as mentioned is very toxic and the flavor/odor are attractive to animals and small children. There are instances of AF being used by women to murder their husbands, so be very carefully.
Jess