I use a product called Waxoil on the underside of my car and its great for protecting against rust! I give a light coat over the fuel and brake lines, you can get this in a spray can but i have not tried that out yet. Hope this helps.

Kell

Castrol CL. Waterproof grease.

Don't forget to buy yourself a aerosol can of Waxoyl before getting down and dirty, most likely be some points where the pipes disappear over subframes etc at the rear and will be almost impossible to reach by hand, and you'll need to spray them..these are arguably more important to protect as they can be an expensive nightmare to change..

Pay special attention to where the pipes pass under clips, they can get very corroded at these points and remain uncheckable unless you remove the clip, Waxoyl aerosol good for getting something under these too.

Whilst down there, check any steel petrol pipes for corrosion.

EDIT, Kell aready suggested Waxoyl, and it wouldn't do any harm to buy a 5 litre can, heat it and splash it about whilst underneath..however i would only do the brake pipes until after the salt has gone and you can wash the underside, if you Waxoyl the underside now you'll be trapping salt underneath.

Edited by gordonbennet on 09/01/2012 at 12:28