Introduction: How to Rust Proof Your Vehicle at Home Like a Professional

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Video tutorial on how to apply an oil or wax spray to your vehicle like a professional, but at home. For this, I’m using my 2006 Dodge Ram as an example. Considering that I live in Canada where my truck is exposed to salt, I want to make this truck last as long as possible. Applying some form of an oil or wax spray is a great way of protecting your vehicle, this will help reduce the chance of components rotting out such as brake lines, fuel lines, floors, frames, rockers, etc. This also maintains the value of your vehicle when you decide to sell it.


oil/wax applicator spray gun with cavity wands

oil or wax rust-inhibiting coating






air compressor

air hose

pressure regulator with moisture s

Step 1: Special Spray Gun

Starting out, you will need a special pressurized spray gun. I bought this online, there are various styles available and unfortunately, this is the most expensive tool needed for the job other than an air compressor. A bedliner style spray gun can be used and I have done this in the past, however, with thicker liquids it may cause issues, and using a makeshift cavity sprayer isn’t as efficient. After a couple of applications with this gun, it’ll pay for itself and I don’t have to depend on someone, wondering if they got every corner or crevice. Based on the application gun, it may have different settings. This one has a fluid control on the rear, you’ll need to dial this in based on the type of spray you’re using, movement speed, pressure, and how thick of a coating you want. What I found was easiest is adjusting the fluid flow so only air comes out when the trigger is depressed, then let the liquid slowly come out based on your preference. This gun also comes with a quick disconnect that allows me to change out various attachments such as a 360 degree cavity wand which is what I used the most, a 90 hook wand, a couple of different fan tips, and another 45 degree sprayer wand.

Step 2: Washing the Underbody

Before applying the oil, a week before I took my truck to the local carwash which heats their water, making the removal of any previous spray or dirt easily wash off. I also used my own multi-purpose cleaner that comes from my local detailing supplier as a concentrated mix to spray the underside of the truck to help cut into the build-up. The carwash I’m using has a storage tank where it keeps the contaminated water so it’s not sent back to the water treatment plant or absorbs into the ground.

I let it dry for a couple of days, you can even wash out the inside of the frame if you wish. I’ve already used a borescope on my frame so I know it’s clean inside. If you were to take your vehicle to a place that applies rust-inhibiting coatings, from what I’ve found they do not wash the underside of the vehicle. Washing the underside does help the new coating bit into any rust or bare metal, maximizing its protective properties.

Step 3: Cleaning Up Any Rust

Next was cleaning up what little rust I had. It was fairly superficial, I used an angle grinder with a cup wire wheel for the bigger spots and a drill with a wire wheel for the smaller tighter spots. The area was degreased, I applied rust-inhibiting paint and let the paint cure for a couple of weeks.

Step 4: Setting Up the Spray Gun

Back to the sprayer, here I am using an oil and wax hybrid mixed coating. I wanted something which would creep and penetrate seams like oil but has a thick self-healing non-dripping coating like wax. I have a 3.8L can of coating, the container for the gun holds one liter, I used about 3L or 3.2 quarts in total on the truck.

Ideally, it’s best to do this when it’s warm so the coating flows better. The day of the application was about 10C or 50F, in order to help the flow of the material, after filling the container, I placed it in a bucket of hot water.

As for the air compressor setup, I no longer have a large compressor so I’m using the smaller one instead. This is a 6 gallon compressor, it will run often but does keep up. While it’s already equipped with a regulator, I used the moisture separator on another regulator to remove any washer which may cause application issues. The rag is just there so it doesn’t rub on the tank.

I found the pressure is best between 90 to 100 psi, however, this may vary depending on the fluid thickness.

Step 5: Spraying Inside the Structure

Park your vehicle in an area where it doesn’t matter if you get any oil spray on the ground. This may stain if you have a paving stone, concrete, or asphalt surface.

I have a small tarp on the ground so the spray doesn’t get on me, you’ll see that in a moment. I would also recommend wearing a respirator and the gloves help with cleaning as you will most likely get the spray on your hands when working with the cavity wand.

Using the cavity style wand, you’ll find various slots or holes created from when the frame was manufactured, insert the wand fully inside. Then squeeze the trigger, applying spray inside the frame while pulling the wand out at the same time. Watch when you get to the end before the nozzle comes out as you can spray yourself. The speed at which you pull the wand out will depend on your pressure and fluid settings. Using the same hole, you can work ahead of the hole and to the back of the hole. Based on the wand length, this will depend on how far of an application it can apply.

Continue doing this for the whole frame. If you’re working with a unibody vehicle, the same process can be applied to the vehicle's structure. While a unibody doesn’t have a frame such as this truck, you’ll still have subframes and enclosed structural components along the floor with possible rubber body plugs that can be removed to access the inner surfaces.

This will be applied on the inside for the full length of the frame, working inside both the front and rear wheel wells using the same style access holes. Only use the factory holes, don’t drill structural components as you may jeopardize its integrity and you’ll also leave a bare steel surface promoting future rusting.

Working with the inner surface of components keeps the application process a little cleaner so there’s minimal risk of getting the fluid on yourself. While this is a no drip formula, it can still drip if too much is applied or you can brush up against a surface.

I did the same for the opposite side of the truck too and even covered the inside of any cross members. Here is the front cross member under the engine, while it’s not fully enclosed like the rest of the frame, it still gets a coating as protection. Areas, where you do not want any coating applied, is the brakes, exhaust, and drive belts.

Step 6: Spraying Behind Body Panels

Moving up to the body, starting with the front and working my way back. First is removing the headlights, this allows for better access behind the front fenders going through factory holes in the body. Again using the exact same wand, feed it inside the hole as far as it’ll go, then pull the trigger while pulling the wand out at a consistent speed.

Other areas also inside the top of the inner fender structure which is a hollow tube and other holes on the inner fender.

The lower support in front of the radiator and the top support too.

Next is working within the structure of the hood. While the higher components are not exposed to as much road debris, it’s still a good idea to have that rust protection as rust can sometimes form between body seams after being exposed to moisture over the years.

I found rear access points to behind the fenders by the hood hinge, so an application is applied here too. Look for anybody holes which can give you access to different areas, this will ensure every area is sufficiently coated. The edge around fender openings, rocker panels, and doors are the model comment areas for panels to rot out.

The rocker panels get an application, these trucks are known for having the rockers rot out. While we’re here, the cab corners are another area when gets an application too. This can be done from the underside of the truck, other vehicles may be required to have trim comments removed along the door’s edge or you can also drill holes in the body panels using a step drill, then cap the holes off after. Oil spray access caps can be purchased at your local auto parts supplier. This truck has had some body panels previously drilled as shown by the black plastic caps. When the door is open, you can go in from the hinge side to access the backside of the front fenders too.

While my doors are also drilled, you’ll have door drains at the very bottom edge, in this case, they’re hidden behind the rubber door gasket. Here you can fit the wand inside, then apply the coating along the bottom and side seams of the doors. The doors are made in two pieces, an inner and outer shell with a crimped wrapped around the edge which can be an easy target for rust.

It’s important to flush out the fenders where you’re washing the truck, most trucks seem to trap quite a bit of road debris on the top between the inner and outer finder. For this Ram, there are a series of holes that allow you the flush out the dirt with water, make sure it’s dry, then the rust-inhibiting coating can be applied. This is where I switched over to the other 90 degree wand tip which seems to give the best access. You can also feed the 360 degree wand sprayer from the bottom up. Spray on the exposed area of the inner fender, along with the inside surface of the box sides.

Moving to the rear of the truck, remove the taillights and this will provide some access behind the fenders and the lower rear bedside behind the mud flaps which can be a problem area for rust. The same process would be done for vans, cars, and suvs. Vehicles with enclosed trunk compartments can have some interior trim pulled back to provide access on the backside of panels. A mix between the 90 degree and 360 degree wands can be used.

The tailgate gets the same treatment, I have seen quite a few tailgates rot out, there is a series of drain holes on the bottom that can be used, access holes on the sides, or even the pre-drilled holes if your vehicle has that.

Step 7: Spraying the Exposed Underbody

When done with all the inner surfaces, now is sprayed the exposed visible areas as the final step. This would be the underside of the floor, frame, cross members, brackets, springs, axles, the backside of steel bumpers, etc. Try to avoid plastic or rubber components and just as I mentioned previously, also avoid areas like the exhaust, brakes, and drive belts.

I did get some overspray of the product on the outside of body panels. This can be easily washed off with soap and water or if it’s a little harder to remove, make sure the panel is free of any dirt which can cause paint damage, then use a clean cloth and isopropyl alcohol.

Step 8: When Finished

The coating will appear to have a wet finish once done, products will vary, some may drip, others won’t so be sure to refer to the products application guide. For this particular product, do not drive the vehicle or let the coating get wet for 4hrs.

And after a week, here is the coating. Depend on how much your vehicle is driven, the thickness of the coating, product used, and environment, an application maybe required once a year, every other year, or it may last longer. A wax coating will have more durability than compared to an oil spray.

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