My two cents worth: I was an auto tech from mid 1960's to mid 1970's, so a
great deal of my knowledge is OLD! However, I once had a car come in w/ one
BIG leak in the block, put in that aluminum colored powdery stuff (don't
recall the name) that comes in a container that looks like a roll of nickels.
Many probably know what I'm refering to, it's still sold in parts stores. To
my amazement, it stopped this giant water leak.
Would the stuff work on aluminum? Don't know. Sure worked on cast iron,
though.