you might be able to clean it, bake it to remove all traces of surface ol, and use an epoxy type sealant to coat the inside, to stop the seep. cast aluminum is porous to a small degree, and from piece to piece there will be variations. you might have been the unlucky guy, to get a porous pan. you dont want to seal it externally, just the inside surface, if it really bothers you.

"When Tyranny Becomes Law, Rebellion Becomes Duty"