Rust on underside???

[alfantastic]

Hi, looked under the car the other day and noticed that general areas had patchs of rust on them. Namely, the metal bracing bit (sorry, don't know tech name) across the bottom from wheel to wheel. Also other areas such as brackets and a few bolts. The rust isn't bad but noticable and a little concerning. It's a 2003 model N16. I know all cars rust eventually, but is this any cause for concern for a car of this age? Would a regular good spraying of WD40 on the affected parts keep rust at bay.
Can anyone help, please?

 

[rhyd4]

rub it all down and underseal or spray them up with some tough paint is the best, rust likes air and water