Oil as undercoating to slow down rust

Joined
Mar 21, 2004
Messages
27,541
Location
Near the beach in Delaware
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.
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.

The proper product will creep and fix areas where the product got scratched or washed off.
 

JHZR2

Staff member
Joined
Dec 14, 2002
Messages
48,614
Location
New Jersey
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.
The issue is that in some enclosed areas where water stands, some of these products can lift or flake.

BTDT with my experimentation with cosmolene in the doors of my Dodge Ram.

9FF66089-4414-4CA7-B194-F65746B0F25F.jpeg
 
Joined
Apr 7, 2022
Messages
58
x2 on Noxudol. Noxudol 300 for chassis and 700 for cavities. It’s the same product Toyota, Isuzu, etc. have used for corrosion related recalls and mitigation. Stays soft, does not wash off and contains active chemicals to stop corrosion. Noxudol 700 (for body cavities) has excellent creep characteristics and stays active for a long time. I’ve tried a lot of different products over the last 35 years or so (heavy winter salt here) and nothing works better. Krown and Rust Check wash off within 1 -2 hours driving in rain. Fluid Film is a bit better, but still washes off far too easily in winter conditions.

Minor touch ups are all that is required yearly…It’s a bit more expensive on first application but rapidly pays for itself in subsequent years.
 
Joined
Mar 30, 2015
Messages
9,329
Location
Lake Havasu City, Arizona
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 .
View attachment 100686 View attachment 100687

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.
 
Joined
Mar 30, 2015
Messages
9,329
Location
Lake Havasu City, Arizona
..... BTDT with my experimentation with cosmolene in the doors of my Dodge Ram.

Cosmoline is the one product I never tried, but admittingly should have when I lived in that climate. I think it's waxy toughness, and it's ability to stay put make it a good choice.

The military stoired weapons coated with it for a good reason. However, like with most products when used in the automotive world, it would require reapplication.
 

wlk

Joined
Aug 21, 2016
Messages
222
Location
Pennsylvania
Woolwax is a thick lanolin based undercoating that works great. I use the black, it looks very nice and goes on thick. What may wash off over the year can be easily seen w the black and you know where to apply when touching it up the following year. Woolwax is a bit thicker than FluidFilms and lasts a little longer.
 
Joined
Aug 26, 2009
Messages
302
Location
UK
M119 you are so lucky your roads are not salt srapyed!
If you live neat the sea, be aware that sea breeze is just as deadly as salted roads

Oil film will provide protection against corrosion. But will wear off quickly in 50%+ humidity even if you don't use your car.

You can use thicker oil like gear oil which will last longer. They will both collect dirt dust & grime as well!

Here is what I did:
clean the underside of the car (snow foam or similar) drive the car, then let it air & dry for a day.
Used rust blocker spray
Used underseal with waxoyl in it.

The important point is to saturate the rust with product like waxoyl which will stop it from being exposed to air. Unfortunately waxoyl despite being great at combating rust, need a top coating at it is not strong and stays sticky.
 
Joined
Apr 7, 2022
Messages
58
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.
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.

The key is the right product, applied well (the franchise shops I've used have all been crap with respect to coverage) and maintained yearly. I also go over our cars each spring and address rock chips etc with some prep and touch up paint. Over the last five years I've set with a decent set of cavity spray tools, and have the luxury of a hoist in my shop. It takes about 5-8 hours of labour on each car to the do the first treatment which includes a thorough spray wash of the chassis, drying, and then pulling off fender liners, chassis shields, and some trim bits, lights etc. to get at critical areas. This is what Noxudol 300 looks like after four years. You can see I have just applied a bit of touch up on the rear suspension which gets beat up here after a salt/sand winter. This last winter was a record setter with respect to both cold and snow for us.

IMG_77233.JPG

There are only two products I've ever found that contain actual corrosion inhibiting additives along with the carrier. Noxudol 300/700 and Noxrust 712 AM, both used in Toyota's various frame/rust recalls. They are wax based, and water borne for application.

I'm about 100% positive that the Toyota engineers chose these materials because they are easy to spray, don't swell rubber (like lanolin based FF and Woolwax), don't wash off and actively combat corrosion. Internally, the material is there for the life of the vehicle. Externally, you'd need about 200-300ml per year to touch up areas directly impacted by wheel wash.

This 3 year long term test is about dead on with my experience...but I'd add that the Noxudol 300 (applied to exposed chassis) is about as good is gets resisting sand/salt "blasting" that a road car sees in our climate. This test was with respect to the Noxudol 700 https://www.auson.se/wp-content/uploads/2020/03/rusttest_noxudol_700_classic_monthly_uk_1.pdf

The 700 creeps 5-7 inches after application, and in that long term test was shown to have reacted with existing rust to stop it.

I use Fluid film on my snowblower for summer storage, but it is gone (from the auger/chute area) after pretty much the first snowfall. On the outside of the blower, it's ok as it does not see much in the way of wash during a winter. There are no seals/rubber that I'm worried about on a snowblower either. I don't use it on our cars anymore.
 
Last edited:
Joined
Jul 30, 2003
Messages
2,177
Location
GA
My old Taurus came with a self-oiling system. When I replaced the oil pan gasket I must have knocked something loose because it doesn't work anymore.
 
Joined
Dec 16, 2009
Messages
116
Location
Rhode Island
If you can get Fluid Film or Woolwax in France I would go for that. My next choice would be the chainsaw oil because that usually has a tackifier which will help it stick.

I bought a 5 gallon pail of the black dyed Woolwax and can say the stuff goes on thick and sticks well even after a full year. I can see a few spots that did wash off over the winter which I'll be touching up this month, but I can see paying a little more for the dyed version is going to help avoid going over areas that are already coated.

I would avoid spraying used oil not only for the environmental concern but due to the fact that it is a known carcinogen. I wouldn't want to be aerosolizing that and potentially getting it on my skin if I didn't need to.
 

M119

Thread starter
Joined
Jan 3, 2020
Messages
815
Location
Brittany
This video gives some interresting ideas like using a dye... They seem to use a mix of lanolin and mineral oil.
 
Top