how should i fix this? can i do it my self or should i bring to a body shop?



funny thing is that my buick had the same problem and in the same spot. u guys might wanna check your passenger side rear wheel well for the same thing.

Looks like its only surface rust?
sand it down and get out all the rust cover with primer and under coating.

do i break off the loose under coating?

You can pick at it but be carefull not poke a hole in the weak metal.
Better to use a wire cup brush and a grinder to clean that gunk up.

Remove all the loose material. If you have a wire wheel, use it to clean up that area. You will then have a better idea what you're up against.

Yep, mine did that in the same place! I cleaned it up, neutralized the rust and put some underbody filler to fill it up. You'd never know something was there now.

Make sure you use a rust neutralizer like Foote did. Then once you are all set hit it with some rubberized undercoating ... once it gets dirty again even you'll have trouble telling.

whats a rust neutralizer? would a primer have a rust neutralizer in it?

When you go get paint, look a bit to one side of the spray paints. You'll find all kinds of rust neutralizers. Some turn rust into primer, some require a primer coat afterwards...

It'* good stuff that stops rust.