Try the String protector from rustyfingers RustyFingers.co.uk
If you havent as yet solved your problem with your rusty strings then try the string protector from above, dont use WD 40 as this could damage your fretboard by swelling the wood.
The string protector comes with a microfibre wipe,for you to wipe your strings before applying the protector.
This has protected my strings and my fret wire from corrosion, and has prolonged the life of my strings.
