There ya go. Due to global warming, we won't have to worry about this in a couple years.

- Scott

The other issue to watch for is gravel.

The wheel arches are not well designed and the flared painted metal at the outside of the wheel arch will get chipped if you drive on gravel roads or if the salt contains gravel ..... these are old cars and the bodies are just not as well designed to avoid corrosion as a new car.

If you drive an old MB in the winter in true winter territory it WILL rust quite quickly. End of story.

I have a 83 300D that has spent all but two of its years in Vermont, where it is quite salty in the winter. It definitely has rust, but you can tell that the PO chased it down whenever it popped up by using touch up paint. As a result the body looks pretty decent.
The more troublesome areas are those that you can't see while standing up, but preventative measures can make the car last a long time. I have seen a lot of this cars that are totally rusted out and they all rust in the same places.
Here's my treatment:
1.Remove the rubber liners under the fenders that are supposed to keep the dirt out.
2. Spray out through the drains where the hood hinge areas. Make sure that this area is always free of leaves, dirt, etc.
3. Continue to spray downward from under the fender toward where the panel is bolted to the body just in front of the door. Use a lot of water, and let dry.
4. Repeat procedure for rear wheel wells.
5. Remove any loose undercoating from these areas and from under the car using a blowtorch (careful!) and a scraper.
6. Buy an undercoating gun and apply chainsaw bar oil liberally to all of these areas. Spray a lot in the trailing arm rust cup where the rear shock attaches. Also coat around the door gasket and under the plastic door sill.
7. When you wash the car, pay particular attention to flushing out from behind the moldings and rubber trim.
8. Make sure none of the windows are leaking and allowing water to get into the cabin
9. While you may not want to, I also spray oil on the entire exterior of the car below the trim line and then go on a long ride on a dusty dirt road to cover the oil.
The idea here is that in my experience is is not so much the salt (which washes off easily) that will rust the vehicle, but the sand that the road crews usually mix it with. The sand builds up and traps moisture which causes rust. So pay particular attention to wherever sand might accumulate.
I am of the belief that washing you car in the winter -in a severe environment like Vermont or the Upper Midwest -is the WORST thing you can do as is puts moisture in strange places where it combines with trapped road sand and salt. Better to wait until the spring when you can really flush it out and let it dry. Also, try to drive the car in as many torrential rainstorms as possible to wash the underside of the car.
I make a day each fall to oil my rigs and each spring to wash them out as well a regular washing and waxing throughout the summer, dealing with the rust as it occurs.
No car will last forever in a salt environment, but you can help it last a long time.
Drive your car and enjoy it.

__________________
Pure Vermont Maple Syrup
http://www.squaredealfarm.org

1982 300D Turbo
1983 300D Turbo

What a great thread to find, I'm moving to Madison for graduate school this fall!

After reading, it seems I'll be bringing my 300TD to a better weather area then Minnesota. My car has only been in MN for one season the rest of it's life was spent in Los Angeles where I bought it.

Before I found all the advice here I was planning to buy this kit. Anyone have an opinion on this kit, has anyone used an Eastwood kit? Thanks!

http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=1119&itemType=PRODUCT&iMainCat=373&iSubCat=374&iProductID=1119

Veggie190,
I don't use that kit, but I do use their 2 part rust converter covered with underbody enamel to treat and cover rust spots before oiling.
Please don't use the rubberized undercoating. As soon as it fails (which it will) it will provide more hiding spaces for salt and sand wherever it cracks and peels. Oil undercoating is the best, especially if done every fall. Even better is to heat the oil and melt a tube of grease into it. Think of how the military stores weapons for long term. I have seen 50 YO rifles unpacked and degreased with nary a spot of rust on them and ready to fire.

__________________
Pure Vermont Maple Syrup
http://www.squaredealfarm.org

1982 300D Turbo
1983 300D Turbo

Interesting, I would have thought rubber was the way to go. Is this the two part rust converter you use?

http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=15974&itemType=PRODUCT&iMainCat=373&iSubCat=374&iProductID=15974

Would I need the gallon kit to do my 300TD? As of now I have very minimal rust, there is only one dime sized spot on the body. After I coat it with the rust converter I'll buy an undercoating gun and spray it with oil.

You really know your rust treatment, thanks for the help, my wagon will be thanking you for years to come!

I usually buy the smaller kit each year. It's enough to treat the various rust issues that I have to deal with. A little goes a long way, and I'm not sure what the shelf life is.
Rust is a way of life here, I have a 2004 F-250 that already has its fair share of nicks and bruises. Without the yearly oil treatment it would never last more than ten years.
Regardless, we accept rust, and the passing of our favorite vehicles as a way of life. Maybe that's why we drink so much...

__________________
Pure Vermont Maple Syrup
http://www.squaredealfarm.org

1982 300D Turbo
1983 300D Turbo

Ha! Two weeks ago I looked at an 85 300TD that was covered in rust. It was hard to stomach and if my car turns into that I will definitely be drinking a lot!