I see various sources suggesting that chemically-treated felt pads be placed under battery terminals, to reduce or eliminate corrosion - like these:
Usually either red/black or red/green.
Do these anti-corrosion pads or washers actually work? Is this snake oil? If I place some oil or anti-corrosion chemical around the battery terminal, will that achieve the same effect, or do the pads actually help?
e.g. here is an AutoZone article claiming they really make a difference
In my experience these DO work. They contain corrosion inhibiting chemicals that help keep the terminals from building up the greenish-white powder that is commonly seen on unmaintained battery terminals.
While I have no definitive studies of my own to prove they work, my anecdotal story is that they are an easy and inexpensive way to avoid corrosion.
In my experience the felt washers don't help as much as the corrosion inhibiting chemicals that you can spray or paint onto the connectors and exposed wires. But I do still use them, along with inhibitor that I paint on. The coatings are pretty messy, but car batteries generally are pretty messy so I don't know how much that matters. If you use the coatings you might want to also use terminal caps to minimize how much dirt ends up clinging to the coating.
In my experience over 50 years, battery corrosion on my early vehicles lead me to try the felt pads. Never had any corrosion whatsoever since I started using them
