My two favorites are also my least favorite, odor-wise: Corrosion-X and Eezox. Stinky but great rust prevention!
I used to spend a lot of time messing around with R/C airplanes and boats.
Many were powered by brushless electric motors. The electronic speed control units for these type motors were quite expensive and extremely sensitive to water; one tiny drop and they were fried. By giving them an overnight soak in Corrosion-X and then allowing them to drain off, they became so water resistant they could still function when completely submerged, and one treatment was practically permanent. The stuff is impressive.
I used to spend a lot of time messing around with R/C airplanes and boats.
Many were powered by brushless electric motors. The electronic speed control units for these type motors were quite expensive and extremely sensitive to water; one tiny drop and they were fried. By giving them an overnight soak in Corrosion-X and then allowing them to drain off, they became so water resistant they could still function when completely submerged, and one treatment was practically permanent. The stuff is impressive.