Underbody Rust Proofing DIY

[supton]

Originally Posted By: stephen9666
My experience has been that FF does not really wash off of other areas like frames very easily. My suggestion for an easy DIY would be a thorough FF treatment and a spot touchup every year on the high-wash areas.


I like to do my own tire rotations as it allows me to check brakes and make sure the pads are sliding properly, and other stuff. I often will drag out the sprayer and do touchups in the high wash areas at the same time.

 

[NibbanaBanana]

Originally Posted By: KrisZ

Also, in high wash areas I find regular rustproofing like Fluid Film, Krown or Rustcheck to wash off quite fast, especially from brand new, uncoated components. I noticed that white lithium grease in a can resists the wash off extremely well. I tried it first on my Mazda's AT pan that was showing few rust spots that I could not stop from re-appearing. I treated the whole pan and the attaching bolts with white grease last year, and it is still the same this year.
It was an eureka moment for me. So my 15 Grand caravan will get all the suspension components and oil/AT pans treated with white grease first, and then go for a spray of Krown.


I swear by white lithium grease. The spray on stuff works good but imo the regular white lithium grease in the wheel bearing tub is even better. It seems like it's the only thing I ever found to stop rust once it's started. It works great on brake lines too. I always go over brake lines with it and never had one blow out. It seems like it gets a little dry over time, but never completely washes off.

 

[jcwit]

Originally Posted By: NibbanaBanana
It seems like it gets a little dry over time, but never completely washes off.


Sure does, thats why the military replaced it with a dark grease for lubing a Garand or an M14!

Yes I know we're not talking rifles, just pointing out the fact that white lithium grease does in fact dry out.

 

[George7941]

Originally Posted By: NibbanaBanana
I swear by white lithium grease. The spray on stuff works good but imo the regular white lithium grease in the wheel bearing tub is even better. It seems like it's the only thing I ever found to stop rust once it's started. It works great on brake lines too. I always go over brake lines with it and never had one blow out. It seems like it gets a little dry over time, but never completely washes off.

I find that any grease like product works well for a while and then it becomes saturated with moisture and salt (I am in the salt belt) and it actually begins to promote corrosion. What works are light oils like Fluid Film and Krown, which, because they are renewed annually, stay relatively contaminant free.

 

[KrisZ]

My plan is to use lithium grease in high wash areas and then every year or so top it off with light oil rustproofing to prevent it from drying out. Once a sufficient layer is built up, applying more lithium grease will not be necessary, only occasional spray with lighter products.

 

[doitmyself]

Originally Posted By: George7941
I find that any grease like product works well for a while and then it becomes saturated with moisture and salt (I am in the salt belt) and it actually begins to promote corrosion. What works are light oils like Fluid Film and Krown, which, because they are renewed annually, stay relatively contaminant free.


Hmmm, I never thought about that. Take a dab of lithium grease on your palm and hold it under the faucet and it becomes cloudy and milky due to absorbed water. After a winter of near daily salt baths, it is not hard to believe that lithium grease would be loaded with salt.

 

[KrisZ]

Lithium greases are very good at resisting water, better than thin rustproofing oils. What's the problem?

 

[doitmyself]

Take some silicone grease in your palm, hold it under running water and mix it a bit with a finger. Water will literally jump off the grease. Take some common lithium grease in your palm and do the same thing. The grease will turn cloudy and milky from the absorption (actually emulsification) with the water. I also tried this with SilGlyde and it performed similar to lithium, maybe a tad better. Do you want a salt laden grease sponge sitting on your steel?

Don't believe me? Try it.

 

[jcwit]

Boils down to the Professional shops know what to use and what they're doing.

Yes there a few here who would know what they're doing, but that also means that there are a bunch that don't.

 

[KrisZ]

Originally Posted By: George7941
I find that any grease like product works well for a while and then it becomes saturated with moisture and salt (I am in the salt belt) and it actually begins to promote corrosion. What works are light oils like Fluid Film and Krown, which, because they are renewed annually, stay relatively contaminant free.


Please explain to me how light oils "stay relatively contaminant free" and grease wouldn't? Annual re-spraying doesn't renew anything, it simply puts a fresh coat of oil on top of the old one. And have you actually inspected your undercarriage after only one year of being sprayed? It's filthy and black as tar. Meaning your next coat simply covers all that dirt, grime, salt and everything else that got stuck to it. Grease will do the same. Yet is still works as it should and prevents corrosion.


Originally Posted By: doitmyself
Take some silicone grease in your palm, hold it under running water and mix it a bit with a finger. Water will literally jump off the grease. Take some common lithium grease in your palm and do the same thing. The grease will turn cloudy and milky from the absorption (actually emulsification) with the water. I also tried this with SilGlyde and it performed similar to lithium, maybe a tad better. Do you want a salt laden grease sponge sitting on your steel?

Don't believe me? Try it.


Well, spray some FF or other rustproofing oil in a container, put some water in and stir. The exact same thing will happen. Why is it of little importance? Because the rustproofing oil, grease or whatever is simply sitting on the surface and is not being mechanically agitated and mixed with water.

As I mentioned above, after just one year of driving with the undercarriage being sprayed, the coating, whether oil, grease or wax, will be filthy and full of contaminants. The next coat will simply cover all that and I have yet to see anybody completely remove the old coating before applying a new one. Why invent problems and theories here about salt contamination? It's based on nothing more than feelings.

 

[KrisZ]

To add to the above.
I think you guys are missing the point about grease. I never said to use the grease exclusively. It is thick and heavy, meaning it will resist wash off, but it will not creep the same as oil. I mentioned grease for use in high wash areas, and it can be topped off with regular oil rustproofing. This way it will not dry out.

 

[George7941]

I am not inventing problems and theories about salt contamination, my opinions are based on real world experience.

I take care of a small fleet of trucks. It is a lot of work keeping bolted electrical connections (like starter cable connections) corrosion free. If ignored, green corrosion eventually destroys the cable ends and then it can create a lot of work because cables are seldom long enough that you can cut the corroded end of a cable off and then crimp on a new terminal.

I tried keeping the terminals coated with grease but found that eventually, once the grease is saturated with moisture, corrosion occurs at a greater rate than if nothing had been applied to the terminals.

I now spray the terminals with Corrosion Block and I find that as long as I spray every couple of months, the terminals stay pretty clean.
http://learchem.com/products/corrosion-block.html

The difference between grease and light oils is that grease is thick and can hold a lot of moisture when contaminated whereas the light oils form a very thin film incapable of holding much moisture and this film is easily renewed every couple of months with a fresh film.

 

[Ducked]

Originally Posted By: doitmyself
T Take some common lithium grease in your palm and do the same thing. The grease will turn cloudy and milky from the absorption (actually emulsification) with the water. I also tried this with SilGlyde and it performed similar to lithium, maybe a tad better. Do you want a salt laden grease sponge sitting on your steel?



Sounds like you're looking for a liquid or semi-solid that can't be mechanically mixed with water or other solids.

Don't think you're going to find one in the local universe.

A solid wouldn't mix, but then you've got a paint. The snag with paints is they don't creep or penetrate very well, and, once set, they do trap water against the steel MUCH more efficiently than the emulsions you describe, which aren't completely impervious, and so will release water.

I speculate that a very slow setting paint MIGHT have some advantages, since it would have time to creep along seams and penetrate into rust before it sets. Vegetable oil behaves in this way, and I use it on components with deep rust that would be a hassle to remove thoroughly, such as brake drums. I've also applied it as a paint in high wash areas such as wheel arches.

For general rust proofing I think even this slow-setting behaviour is undesirable, so I mix it with mineral oil to stop it, or at least to slow it still further.

This is of course all speculative. I don't have any experimental data on its effectiveness.