Rust and road salt
 

Yes and no, if it's kept in a DEHUMIDIFIED environment then no chemical reaction will occur, or if you live in a desert and ambient humidity is extremely low, or if ambient temperature is too low for humidity to rise.

However if you are in a humid environment then yes it can still rust. I strongly encourage you to drive it down to a car wash and hose it off well, especially the undercarriage, just to make sure you aren't causing any corrosion.

The painted surfaces aren't the ones that will corrode, it's all the cracks, crevices, and unpainted surface that you need to watch out for as well any any chips in the paint. I strongly recommend people do touch-up paint in the fall for exactly this reason.

As long as it's always below freezing the humidity will be really low and rust will be kept to a minimum...

If you're feeling bad about abusing your old G buy a few cans of fluid film and empty them into all the places salty water forms as well as into your rockers etc

Yeah, 260k miles or something right? It lived a long hard life, now you've got a clean one that you can keep clean so look on the bright side!

If you daily drove a G for that long, you know where all the snow and water goes and where it rusts out. If you really want to stop your new G from not rusting but don't want to constantly worry about it it's worth spending a $50 and a couple hours rustproofing all the trouble spots and forming a barrier against any future issues - use a drill, rubber plugs, and rustoleum if you have to get inside door sill and quarter panels, and never worry again.

That's probably typical on every car everywhere over 5 years old. The tires throw up debris, chip the paint leaving bare metal exposed and rust develops.

Typical but if you want to make that car a forever car that's a good stage to hit it with some sandpaper and seal it up real good again, filling the lip with a persistent oil such as fluid film when you're done

After

If I were buying that car and planning to drive it in winter I'd give it a full rust check under the side skirts and everything and take any neccissary actions to prevent any future rust from forming: fill bolt and drain holes with fluid film, sand and rustoleum any undercarriage rust spots, etc...

Seems like a lot of work until you realize you won't have to worry about that car rusting again for a long while.

Once the paint is chipped off then rust will form on metal simply due to humidity. It's important to use a paint pen to correct any chips as soon as you find them (if it's never been done then expect to correct 100-300 chips the first time), anything that's chipped on a nonmetallic surface such as the front bumper is less important since it CANT rust but still important to fix since a chip can get much larger if water gets under the chipped edge and freezes.

Undercarriage rust depends greatly on whether it's driven in the snow and whether they salt the roads, liquid deicer won't corrode the bottom side of your car nearly as bad but it's still good practice to get under your car a couple times a year at least and go to town with a couple cans of aerosol rust preventative, also a good time to hit every single nut/bolt with penetrating oil because eventually EVERYTHING gets unbolted for repairs and it's the difference between bolts that break off vs. ones that don't.

I've been getting oiling each year on my car (cobra) and it's been doing an amazing job at rust prevention. Highly recommend rust prevention applications every Halloween for the winter!