I am going stupid myself. I took the advise of a gunsmith who told me to clean out that ammonia with brake cleaner and then coating it with a good oil.

It is a concern. But after cleaning numerous times on a gun, I recently looked at the bore and there was no pits or anything. So I must be doing something right.

I am just not sure that motor oil alone displaces moisture but might trap it? does that make sense or am I way off base. I am not a chemical or pretro engineer so am open for an education for one that might know.