is aluminum rust proof
Aluminum corrodes but it does not rust. Rust refers only to iron and steel corrosion. Aluminum is actually very prone to corrosion. However, aluminum corrosion is aluminum oxide, a very hard material that actually protects the aluminum from further corrosion. Aluminum oxide corrosion also looks a lot more like aluminum (dull gray to powdery white in color), so it isn't as easy to notice as rusted iron.
While aluminium doesn't rust, it often becomes dull from corrosion, and is often encrusted with brake dust, calcium, lime, tarnish, grease, oil and hard water stains. Simply washing it off will not work, you need something stronger and more effective to do the job.