[Lippyp]

Thats why we use wax, it creeps into seams, is actually slightly self healing so if it gets scratched it'll seal it self and it stops the salt water getting into seams and cracks. When I replaced the rocker on my truck it got a good blast of wax inside so it'll never rust from the inside out. I use a two foot long flexible tube with a 360 degree nozzle on the end, you insert it into a cavity, drilling a hole if neccesary and then withdraw it whilst spraying giving it a twirl along the way. The wax I use comes in a big rattle can, stand it in a bucket of warm water so its nice and runny when you spray and it gives a fantatsic coating. This stuff has been salt spray tested and gets used by industry on oil rigs etc.