Originally Posted by machinist42

It is not too late to apply an interior coating to your frame, if that's what you choose to do. Their is no clear consensus on whether it is necessary, and my personal experience is inconclusive. I live 500 feet from the ocean, and I've treated some of my bikes and haven't treated others. (However, I should note I flush the tubes of my bikes with phosphoric acid when I acquire them, and that does leave a corrosion resistant coating, so they sort of are "treated", though not in the same sense as you mention. So far, no internal corrosion on the "untreated". Your experience may differ.) It can't really do any harm?

As an aside, the "treatment" I've been using is a new product of the WD-40 company which antique gun aficionados have been touting: "WD-40 Specialist Long-Term Corrosion Inhibitor." It's inexpensive as it's new. (I am not affiliated with WD-40, nor compensated.)