Thank you all from your valuable inputs.
I had used different spray can primers with mixed results, but all of them didn't last many parts so I have to switch to something more economical with the wings coming up.
I went to auto parts store and they gave me this 2 part epoxy primer and they said it works with aluminum. It looks very nasty stuff
And here is the product home page:
http://www.sikkenscr.com/en/products/Primers_Fillers/Primer Surfacer EP II
The instructions say I have to use a reducer which I didn't buy. Will off the shelf thinner do the job?