^ I have always used Vaseline (trans: petroleum jelly; for our American friends ... ) for battery terminals and the like. Stops sulphating as well as rust pretty much forever, AFAICT.
After dressing all the surfaces with something like 100-200 grit wet & dry paper, a fairly thin coating rubbed into both sides of the terminals/earthing points seems to work miracles, and doesn't cost a poultice. Like a pound tin of grease, a small jar of Vaseline seems to last indefinitely! I am still using a tiny one I purchased about 30 years ago ... I will kark it before I use it all up ...
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With battery terminals, I use the edge of a file to scrape upwards vertically on the battery terminal posts all the way around to expose bright lead. Don't take too much off - just enough so that the bright metal is exposed. This method ensures that the post is slightly uneven so that the clamp bites hard with a good physical and electrical connection.
Use a knife blade on the inside of the clamp terminals. Then smear both sides with Vaseline before reconnecting. Again, doesn't have to be much, just a thin coating.
I forgot to mention: you should also check where the battery is earthed to the body, and undo and check the various earth points of the engine block to the body. Don't know how many of these there are on the SF, but on both my old Impreza and the SG there are a number of them.
