Waxoyl for a defender

[pgtips]

After a bit of googling I realize this is potentially a controversial question.... My 1990 TDi needs tidying up. The rear door is corroding (I need a new door), and rust forming around bumpers and visible bits of chassis. Is it worth a Waxoyl treatment (for chassis & bumper)? And if so, does this remove rust to then re-paint (on bumpers), or does Waxoyl effectively become the outer coating?