How do you prevent car body and frame rust?


I live in Pennsylvania, the winter road salt capital of the world. I was just informed that my current car’s frame was rusted away & couldn’t be repaired. Since I haven’t much money a used car is the only option & I’m in the process of going into debt to buy an older but rust free vehicle (1999 Chevy Prizm) I want this car to last a long time so how do I keep it rust free?

Should I have the car body undercoated with oil once a year? During winter “road salt” season should I go to the car wash once a week & spend most of my quarters spraying water underneath the car?

I live in an efficiency apartment & don’t have a garage filled with car stuff–heck I don’t even have a garage, my car is always parked outside. What do I do to keep my new used car as rust free as possible?


It’s not the under body that rust first…it’s the areas of mosture collection, running boards,door seams rear quarters, fender/liner joints etc (anywhere a drain hole is ineffectual). A juditious application of oil to these parts does go along way to preventing rust…manufacturers have come a long way in including materials that fight rust, reluctantly and mostly as a sales ploy. No one is really looking out for the consumer except the consumer. Frequent washings and dammage(scratches) control goes a long way to minimise rusting. I’ve had several Nova/Prisms, and the did like to rust…but NEVER had one of mine rust. even after 10 years in Maine winters with the oil/frequent washing treatments.
If you trade within 5 to 7 years with the newer cars, even in rust belts, it may not be a issue…otherwise it’s another maintenance item.


This is just personal opinion, but I think regular underwashes make a big difference. Can you find one of those new laser touch-free washes that includes an underwash and get there about once a week? Some of them give you a discount if you buy a bunch of washes ahead of time.

Sitting outside isn’t necessarily bad. In fact, they seem to be saying lately that letting the salty snow and ice melt each night in a garage could be worse.


I agree with the other postings about visiting a car wash that sprays the undercarriage. Having a car sit outside may be a plus. A heated garage seems to speed up the corrosive action of the salt.


The oil thing is a good idea . . . but messy. I used to have an old SAAB and the old mechanic who worked on it showed me how/where to oil it, as I recall it was recommended by SAAB? (I’m talking a 60’s SAAB stroker). I’d go with frequent washing of the whole car once or twice a month during the winter, underbosy and all. The fix any rust in the Spring and oil the underbody, maybe one time in the Spring, one time in the Fall. Remember, if you live here in PA (I live in the Poconos) you have to understand that rust will eventually get to your car, if you keep it long enough. Good luck! Rocketman


Spraying the underbody with old drain oil (use a pump-up garden sprayer) will greatly retard rusting. But doing this is VERY messy and is frowned upon in urban areas…


Today’s cars are far different than the old ones. The come with far better rust resistance. Most after market rust treatments do more damage than good.

Look at the old spray the bottom with oil theory. What happens is the oil attract dust and that helps ccreate an environment that attracts moisture.

The best bet is to do little or nothing. I have not heard of any problems of under carriage washing, if not done to an extrean for example.


Undercoating can plug drain holes. That creates resevoirs for water, which lead to rust. I wouldn’t get undercoating. But I would wash the undercarriage a few times each winter at a full service car wash. And wouldn’t it be nice to see a clean car once in a while during the winter?