Well for the sake of the environment use the right stuff like Krown or Fluid Film or similar. Dumping oil (used or new) will eventually get the oil on the road or ground and pollute wherever it ends up. If everyone in the world sprayed oil on their car the world would be an oily mess.In France we seldom use road salt, especially in the west of the country where I live but my W124 comes from belgium and I have a rusty jacking point and rust in one wheel arch to fix which is a classic on older Mercedes. Other than that, the car is solid, I had a good poke around with a screwdriver and I can only find surface rust underneath the car. I'd like to keep it from rusting even more by spraying something oily and I'd like to avoid anything rubbery that can trap moisture if cut/hit by rocks.
Here are the (cheap) options I found so far:
- WD40 : seems way too thin, I think it would evaporate in hours.
- New motor oil : still too thin to cling for a long term, bad for motorbikes if it drips all over the road.
- Used motor oil : same problems, even worse for my health and the environment but free.
- Chainsaw oil : seems like the best option, would definitely cling. A bit too thick to seep in every crevices. What about mixing it with something like mineral spirit or kerosene to spray it? If the lighter components evaporate while leaving the thick oil everywhere, this would be a nice and cheap solution. Seems to work as well as Fluid Film or Krown for many people.
I don't want to spent too much money on other products as I like to tinker and try and I'm cheap. I don't mind if it's a tacky mess under my car, I hate rust.
The issue is that in some enclosed areas where water stands, some of these products can lift or flake.I like to work smarter, not harder. Oil as others said will wash off and require frequent re-applications. IMO that's not working smart. Use a product designed for rustproofing that isn't going to wash off easily and doesn't require as many re-applications. That's working smarter, and doing a better job.
While many here are referring to slowing rust on the exposed-to-wash-off exterior areas, the worst problem in my opinion are the weld seams and boxed in areas. In the salt belt most of the sheet metal rust starts on the inside and works its way to the outside, initially appearing as bubbles under the paint .
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..... BTDT with my experimentation with cosmolene in the doors of my Dodge Ram.
I haven't see that with the Cortec product I've been using. But flaking can happen with some products for sure.
We live in the worst of the salt belt with salt/sand literlaly sand blasting the chassis 5-6 months a year. I also keep vehicles a long time. I recently sold an 1984 Scirocco and 1990 VW Westfalia. Both were driven in winter and both were in excellent shape.This is the main reason I only purchased 2 new vehicles in the almost 40 years I lived in and around Chicago. There is simply no way you can own and drive a car there, and keep it from turning into a bucket of rust.
Today's cars are better at fighting it off, because of the use of more plastics, composites, and things like Stainless Steel exhaust components. But any vehicle sentenced to operate in Midwest Winters is going to rust away. It's only a matter of time.
Things like undercoating, (you pick the product), repeated washing and waxing, "rustproofing", (Companies like "Ziebart", and "Rusty Jones" took a lot of people's money there back in the day), all with little to no effect on long term rusting and body cancer.
The best way to keep a vehicle in nice condition in the "Rust Belt", is to park it in the garage, and buy a beater to be self sacrificed as your daily driver during those conditions. Especially when you factor in what a nice, new vehicle costs today.