Aluminum does oxidize, technically it is not Rust as that is a term reserved for iron. It is also very susceptible to reduction through galvanic action, ie dissimilar metals in contact creating a electrical current that draws ions from one to the other destroying one while preserving the other. Most know this as a sacrificial anode in like in your hot water heater. Aluminum cover on a steel block can certainly get eaten away if the gasket is incomplete or the through bolts are not stainless.
