Greeting:
My 2 cents. This debate has been going on for years without consensus. When the heavyweights can not agree (Jobst Brandt, Sheldon Brown, Peter Weigle, et al.), I figure there can't be much of a problem. There is even debate as to whether there is a problem and, if there is, what are the causes. So how can you solve a problem that may not exist? So,there is no such thing as a wrong answer - do what you think is best.
For me, I just put grease in the headtube, seat tube and bottom bracket shell 'cause I once found water standing there. I am reluctant to pour any kind of goop into the tubes that I, or someone else in the future, won't be able to get out.
r