This recommendation is for the use of common household items. Requires more elbow grease than a buffer, compounds, and carnauba wax but will work. If the oxidation is not too bad, scrubbing the area with cheap toothpaste will help clean it up. Rinse and dry, then wipe it down with Chapstick. The Chapstick will slow down the reaction between your saliva and the stem material. If the oxidation is more severe, then try a "Mister Clean Magic Eraser". The wife (assuming you're married) probably has a few laying around the sink/bathtub!