I have been using pennies on my batteries since I started driving. Just put it next to the negative post. Works great and it only costs 2 cents.

 

After you get it cleaned up with the backing soda and water trick, just put anti-seize compound on it. The aluminum or the copper both work great. They both have an oxidizing inhibitor and they stick and stay on for years, even survive some pressure washing. It's also a lot easier to paint on than grease, and if you don't get both the post and clamp completely covered they can start to corrode again (I found I could not get good coverage with grease).

 

I've used that in the past and it worked pretty well on car battery terminals. The primary solid ingredient in Penetrox, NoAlox, etc, is Zinc powder mixed into a really good anti-corrosion grease that adheres to connections. (I believe it also has some aluminum powder too.)
The special compounded grease is somekind of REALLY sticky, tenacious grease that I believe does as well as any other grease on battery terminals.
BTW, the Penetrox grey fillers WILL corrode to a white color when excessive battery acid gets into the act of reacting with it. It still was working, keeping the clamp-to-post joint clean and corrosion-free, but the surface of the Penetrox layer was taking a beating from the Sulphuric acid...
At work, I use cans of tan colored, No-Ox-id grease on the terminals and intercell straps on the big stationary UPS battery banks. That stuff has the consistancy of somewhere between Vaseline and Paraffin Wax(at room temps).


K.