Treatment with goops/sprays/lotions and potions is often done with a spray nozzle. Mechanics love doing it.
When that is not enough, SB-208B describes what/how to control corrosion once it starts. In non-arid climates with dew points regularly above say 60F for parts of the year, condensation will occur. This is a particularly big deal for the tubular steel frame in our Mooney's, for in places where paint has lost its 'stickum' to the steel, corrosion will begin. Water leaks in around old and poorly sealed windows, poorly sealed instrument bay panels, dorsal air vent with plugged drain tube or other problems. It can run aft along the floor and members and accumulate near the main spar and cause corrosion there. If it enters inside the tubular steel frame, those will corrode from the inside out. That can happen where old steel screws that penetrate the tube wall have corroded.
SB-208B requires regular inspections for incipient corrosion. This requires removal of most of the interior panels. Sometimes corrosion begins in the upper portion of the tubular steel frame, which means removing the plastic headliner and giving those steel pipes a look-see. Depending on climate, hangared/tie-down, IFR/not, do it occasionally.
The steel tubes in our a/c are just itching to start corroding. Coating them with corrosion-X or some such inhibitor is a great thing to do. Working with someone that knows what they are doing is important. Finding major corrosion in a Mooney is the equivalent of standing up when the music stops... Don't let it get bad.
I'm up to speed on this because my bird is in the shop getting all kinds of tubes sanded and re-painted. It is a big job. Pushes one out on the "cost-of-ownership" curve.