This should generate some lively discussion...
Most of us have tried a variety of rust-prevention products. If you're like me, you've found that some don't quite live up to expectations. Many swear by a particular product, but I often wonder if their allegiance is tied to subconsciously defending the choice they made. There are lot of manufacturer's claims published and a lot of one-use testimonials, but not much in the way solid comparative date to back them up.
Back in 2011, 'Classics Monthly' -- one of England's leading auto restoration publications -- began a test of a group of the leading, over-the-counter rust prevention products. The test lasted for three years. The products were split into two categories: 1) those for pre-paint treatment of exterior surfaces, and; 2) those for treatment of concealed internal surfaces (door cavities, frame rails, rocker sills, etc). The results were quite interesting...
https://www.auson.se/sites/default/files/rusttest_noxudol_700_classic_monthly_uk_0.pdf