I use the same funnel for oil and my blasting glass bead tank. just wipe it off with a microfiber, GTG!
Isn't corrosion surface damage due to chemical or electrochemical activity and erosive wear due to high velocity fluids especially those containing particles?Corrosive wear - after all, you have fluid moving in a system. It's going to cause wear, as there are naturally tight bends in any lubrication system. If you push a fluid through a crevice long enough, it's going to make a bigger hole. As well, we're playing with components that could have different polarities, metal types, etc.
You also have essentially mechanical obsolesces. When a part just can't take anymore. It's tolerances go out.
And finally, simply, "breakage" - Things just break for any number of reasons.