If you dispense your beer with a party pump, which uses air instead of CO2 to drive the beer, you can only expect your beer to remain fresh for 8-12 hours. If you keep your kegs warm, and drive them with CO2 through a jockey box or other faucet, they will most likely last a couple of months.
Rust by definition is the result of the oxidation of metal. One engine manufacturer refers to the process of corrosion in aircraft engines as galvanic corrosion which is a type of corrosion caused by dissimilar metals being in close proximity of each other. In this process an electrolyte such as water also needs to be present. Almost all metals will oxidize or corrode.
If an intake valve is in the open position that fuel will enter the cylinder where it will leak past the rings and eventually mixed with the engine oil. This can cause severe engine oil thinning which can lead to engine bearing damage, scorched cylinder side walls and in some cases an explosion inside the engine. There has been reported cases where leaking fuel injectors caused hydro lock because so much fuel has accumulated on top of the piston that when the engine was turned over the engine locked because it could not compress the liquid in the cylinder.