I use Butchers Wax Boston Polish which has worked well for me for over 15 years.
I also am careful to remove any accumulation of swarf or sawdust from CI surfaces
at the end of each day in the shop in the belief that these will attract moisture and
hence support the formation of rust. All my CI tool surfaces look like new even after
10 years. I am near the coast and it can be very humid here for days at a time,
especially in the Winter. I treat my tools with Butchers Wax twice a year, it only takes
a few minutes for each tool.
http://www.bwccompany.com/bostonpolish.html
In the photos below you can see part of the top of my Unisaw. I bought this saw new
in December 2010. The first photo was taken in 2015 and the second just a couple
weeks ago. The last photo is from 2014. In each the CI top looks the same.
I have not had a problem with hand-held tools like planes or saws with rust, but I also
keep the humidity down in my shop by running the heat pump year round for an hour
each day. This is enough in the Winter to keep the temp above 35 all day and in the
Summer to keep the temps in the 70s as well as dehumidify. I don't keep a hygrometer
in the shop all the time but when I did park one out there for a time it stayed below 50%
which I think went a long way toward removing the chances of rust developing on my tools.
So possibly a small dehumidifier might be of help with controlling rust as well as making the
shop a more comfortable place for you to work in.
At work we use LPS-3. There are similar products available which work just as well.
LPS-3 puts a waxy protective film on surfaces its applied to.
http://www.lpslabs.com/product-details/612
