I have to ride over a tidal causeway to get home. On any bare aluminium / aĺloy surfaces and bolt / screw heads, I wipe on ACF50 every autumn. Seems to last quite a few washes and stops any furring. Also prevents any winter condensation from marring polished surfaces. A friend uses a similar product, called XCP. Obviously, keep it away from brakes!
I have used ACF to bring back corroded and furry surfaces, to look like new. Squirt it in the bolt hole, gentle wire brush to get the worst off and ensure it's all coated, leave overnight, then wipe it out. Leave a light coat in there when you put the bolts back in and should be fine.