RUST NEVER SLEEPS
Exterior and underbody rust protection is the perfect solution to resist winter’s relentless assault.
Depending on where you live, winter brings with it slushy, icy, and salty roads and highways four to five months of the year. During that time, vehicles are subjected to a slurry of liquid sandpaper and corrosion-inducing chemicals that produce an electrochemical reaction whenever water, oxygen and bare metal come in contact. Just add salt as an electrolyte, along with the occasional warm, sunny, winter day, and this process corrodes the metal fast.
The ensuing damage is not only unpleasing to the eye, but it can potentially threaten the safety of the vehicle if left untreated or unrepaired. At the very least, rust will render bolts, fasteners and parts seized solid and hard to work on. Nothing is more frustrating than a skinned knuckle trying to loosen a broken bolt while attempting to free a rusty part needing replacement.
If your rig is a project vehicle or seasonal ride, it’s probably on jack stands in the garage being worked on or tucked away somewhere safe waiting for spring. However, if it’s a daily driver, it's taking a corrosive beating from winter roads. What can be done to delay or avoid the inevitable? There are many rust protection practices that are effective, but unfortunately there is no magic-bullet solution. Think of the practices as being in three general categories:
Coatings: This is the broadest category and includes anti-rust paint, undercoating products, and various oil sprays. These can be applied by hand as a DIY project or a specialized shop using a proprietary product.
Cathodic Protection: These are the electronic modules that work by sending a weak electric current throughout the metal parts of the vehicle that disrupt the charge between metal and oxygen, slowing the oxidation process. Frequent Washing: This involves a higher degree of maintenance to remove the catalytic effect of road salt.
No one method or product can claim absolute superiority and car aficionados can entertain themselves for hours discussing the merits of each or their combined effects. But there is a lot of information available so you can make an informed decision about how to protect your rig.
I’ve experimented with all of the individual methods listed above in many combinations. In my experience, only cathodic protection doesn’t seem to help. I confess that I currently have an electronic module on my 2018 4Runner TRD Off Road Premium that was installed by the dealer when the vehicle was new, as part of its extended care rust protection warranty. Am I relying on it, though? Definitely not.
I also believe that the human factor is what differentiates the effectiveness of various products and methods. Rigorous application of all of the methods previously mentioned are bound to be better than letting rust takeover, but which one works the best?
In my experience, the traditional methods of a rust-proof coating of some kind on the underbody – in addition to a wax/sealant on the painted sheet metal and supplemented by frequent pressure washing – produces the most effective protection against rust. Optimum protection comes from being thorough and repeating it often.
I live in a snow belt near Lake Huron where the roads are salted almost daily and it’s not always easy to keep up with the weather for regular pressure washing. I try my best, knowing my efforts are making a difference.
In terms of coating options, I recently narrowed my choices down to two products – Corrosion Free and Fluid Film. Ultimately, I decided on Fluid Film as my go-to for the underbody of my 4Runner. I like the fact that it’s non-toxic and even though it will eventually wash off, I have seen older vehicles that have been regularly sprayed with it and it seems to be effective. It comes in an aerosol can for DIY use and can also be
brushed on. Two applications are required every year, with spring and fall being the ideal times. Corrosion Free is a similar product that I like to use and can also be applied any time of the year.
Smaller, independent shops tend to offer this service and the one I recently took my 4Runner to did a great job. Before they applied these coatings, I had to make sure the vehicle was thoroughly cleaned and all mud residue was removed, and the entire chassis and floor pan were as clean as possible. It’s not absolutely necessary for the vehicle to be dry, as both of these products displace water, which is one of the positive attributes.
The human factor I mentioned earlier became evident from this shop as well. They removed the skid plates and sprayed all the nooks and seams where rust can eventually form and avoided all the plastic components. They only apply the compound where it’s needed. In my case, I asked them to only spray the sheet metal behind the grill and the lower firewall in the engine bay, as I like a clean dry engine area to better diagnose leaks. It also makes servicing cleaner and easier.
The end result is an ideal coating as the Fluid Film tends to seep into the seams after application. I plan on doing this annually along with regular pressure washing at the local drive-in wash, hoping it will slow down rust deterioration and add a few more years to my 4Runner.