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Undercarriage rust treatment and rust prevention


Undercarriage rusting usually happens through chemical reaction. The latter occurs when there is air and water (humidity) contact with the metal. Called an electrochemical reaction, this means that there are electrons that are being exchanged and with salty water (rain) being extremely conductive, this speeds the rusting. To prevent this there are a couple of things that can be done.

If your car is old and prone to rusting, then it is advisable not to let it get wet from the rain or even driving in extremely rainy weather. As an added precaution, you should never park your car outside.

If your car undercarriage has access to water and air on a constant basis then the chemical reaction will be faster. For this reason, it is better for you to cover your car when not in use or have the undercarriage coated with anti-rust paint. It is also advisable to repaint the undercarriage regularly since rocks and water splashes from the road will wear it off, the thicker the coating, the better. You might also want to use some rush inhibitors primers as well when coating it.

Electrochemical reaction (rusting) attacks some metal faster than others. If you can find some of those metal, take a sheet and cut it around the size of the undercarriage and place it where you think it might be prone to rusting. Sacrificial anode is what we call this method. These method are used a lot onto ships who have steel hulls and are always into contact with water (obviously). The most common metal that are used for the sacrificial anode are magnesium and zinc. Metal will rust anyway, and the point of placing this protection is that the main steel metal of the undercarriage doesn’t rust. As such magnesium or zinc is used to save it. Also you might want to check it regularly to know when to change your sacrificial anode. Let’s now take a look of some products that can help with it.


Fluid Film 1 Gallon Can Rust Inhibitor Rust Prevention Anti Rust Coating Undercoating

Fluid Film is one of the most trusted brands in terms of rust treatment and prevention.


Pros and Cons

The pros of this rust and corrosion undercarriage protection and prevention is that it contains no solvents. It is extremely easy to apply in its thixotropic liquid form. In addition to that it is non-toxic meaning less harm to you. Since it contain no solvents, it will not dry out. This rust preventer and controller will provide the metal with a coating that will prevent corrosion or control it as well as being long lasting. It works mostly with all metals and like advertised does stop rust on contact, although you need to wait a few minutes for it to react to the metal. As a plus, during snowy weather, you can even use it onto bolts and tools so that it does not break when frozen.

The only con we found although can be bypassed is that due to the thickness of the coating, you may have to purchase a spray gun from them, since they generic one won’t work, but you can still apply it with a brush if needed.

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Fluid Film 11.75 oz. Spray 6-pak 

Another one of Fluid Film’s products.


Pros and Cons

This aerosol spray is very good for convenience since you get the same product in a pack of 6 and you don’t have to buy a spray gun to use it. As the other ones of fluid films coating this one works as well as the others and the plus side to it is that you can get to hard to reach angles under the carriage and only wait a few minutes of it to dry.

As a matter of fact, there were no cons for this one.

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Fluid Film Undercoating Kit 1 Gallon with PRO Spray Gun 

One of Kellsport Products and it is sure to be of very high quality.


Pros and Cons

This kit is one of the best you’ll get with the 24″ extension wand as well as the spray cap. The latter makes it easy to apply the coating which is mostly oil based. You also get the touch up brush if you want to smooth the surface as well as 2 spray guns. 1 Gallon is all you’ll need and some will be left even for future uses. The latter is also safe. The coating is also extremely thick and is sure to protect your undercarriage or stop any rusting that has already started. The container (spray gallon) will also warm the liquid to make it looser for spraying which is very convenient

As a matter of fact, we couldn’t find any cons with this one.


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Fluid Film Spray can Extension Wand 

Another one of Kellsport Products and we know we are going to get a quality one.


Pros and Cons

This product being only the wand extension is convenient to use along with the kellsport spray if you plan on getting it. The spay being already convenient to get to hard to reach angles and providing the same high quality coating film is aided by this want to get to smaller spaces which are even hard to reach for the spray. Overall it is a good equipment or accessory.

As a matter of fact, we couldn’t find any huge inconvenience to be classified as a con for this product.


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Now that we’ve reached the end of this review, it’s time to reveal our pick but before getting to that, we should add that even though we’re choosing one product, doesn’t mean the others are bad since they’re all pretty good. Now without any further ado, the one we would most likely bet on is the Fluid Film Undercoating Kit 1 Gallon with PRO Spray Gun. The reason is simply because we couldn’t find any cons for it and the kit is pretty good overall.