I know my Dad painted his Mom's barn with the aluminum paint before she passed, and it was still good almost 20 years later.
Did a chainlink fence which added a bunch of years to it (though he had to throw the jeans he was wearing away after).
Painted a Farmall F20 with it just to keep ahead of the rust, since it was the most durable paint he knew. It did a reasonable job of protecting that, too, even if it did look a little silly being bright silver. When it had aged another decade, it looked pretty nice that way.