Aluminium relies on oxygen to protect itself via aluminium oxide, once you change that relationship you must maintain the protection which is difficult.
If you are concerned about corrosion
seek out a product called BoeShield, it's a coating designed for internal wing surfaces on airplanes, great for outboards, seriously ally is best left to fend for itself unless acids or alkalis are involved.
or filth are the enemies where crap accumulates and creates cells where corrosion
gets going BECAUSE oxygen is depleted from it...