Rust-Proofing

About 4.5 years in, I took a look at the underside on our regular Prius. A lot of the bolts were looking really rusty. Same thing for a lot of the suspension components, especially around weld points.

With some of the plastic underpanels bolts were used, and some were virtually rust-welded on; if I'd left them another year I think the heads would have snapped off. That DID happen with one plastic-to-plastic connection in the front fender, but not so important.

Bottom line: paying someone to willy nilly spray under there is not very effective. This is a good DIY project though. Do it one end at a time: raise the rear and put it on jack stands, then repeat at the front. There's a lot of small bolts and coarse thread screws. Wherever possible take those out, saturate them with an oil, and reinstall.

I basically wiped/brushed components, then applied a oil/wax preservative. I used Lloyds AD2000, but there's a lot of options. It comes with in a spray can with straw, but mostly I applied it with a toothbrush, for more control. I kept an oil drain pan underneath, to catch the drips and grit.