Garrett,
This may sound odd; an old timer told me to wipe any nonferrous metals with
white vinegar as a prep/etchant before painting.  In a pinch, I have used
this on aluminum instead of metal conditioner.  One place I used it was on
some roof flashing fabricated from mill finished aluminum sheet and painted
with Krylon aerosol paint.  No primer was used.  It has been exposed to the
elements of the Northeast for 17 years and the paint is faded but still sound.
Rich