Several years ago, when I bought a rust-free 1987 Subaru GL in Arizona and brought it back to the Northeast, I was concerned about how its paper-thin sheetmetal would fare against the scourge of salt that state and municipal transportation authorities order dumped on snow-prone roads each winter. After doing a bit of research, I came up with something that looked like it would ward off salt and moisture from my car's chintzy steel (along with regular washing and keeping a close eye on paint chips and scratches). My secret weapon? An oily rust inhibitor from a Cheektowaga, New York-based company called Carwell.
Rust, the sworn enemy of vintage car and truck owners everywhere, is as inevitable as death and taxes. Repairing it can be costly, and doing nothing about it a surefire way to reduce a perfectly good vehicle into a leprous Swiss cheese of ugly, damaged metal and unseen brake and fuel line problems. The best way to handle rust is to prevent it from attacking in the first place. It may be difficult, but it's not impossible if you think of rust prevention like you do drivetrain fluid changes.
I'm happy to report that, like the Rust Belt-based truck fleets Carwell sprays its rust inhibitors onto at the end of every summer, my car has remained cancer-free through several winters worth of blizzards and salty slush. Carwell's T-32 (called CP90 in their smaller-sized containers) is an oily pink liquid that sprays onto the undercarriage and into doors, rocker panels and fenders through a series of specialty nozzles. It has worked so well that I've started using it on my two-car fleet of decrepit Malaise-era GM cars, too. I promise, I'm not a shill for Carwell; the stuff actually works. There are alternatives like NH Oil undercoating that promise similar effects as well.
If you live in the actual Snow Belt, there are retail locations here and there that will spray rust inhibitor on your car. In the mid-Atlantic states—and many other places with in-between climates whose state and municipal governments use corrosive chemicals to keep snow and ice off of road surfaces—rust-proofing isn't really something many people do on a regular basis. But even in the warmer Southeast, cars and trucks, especially older ones, tend to rust when frequent rain and humidity creep in. Essentially, rust isn't exclusive to places where snow falls in the wintertime.
Why regular rust-proofing is a good idea (and how to do it)
As I noted a few years back, Carwell, in addition to working on several thousand private vehicles each year at its retail spray shop near Buffalo, New York, services several thousand more school, fire, military, and commercial fleet trucks around New York State. Fleet managers I have talked with reported good results, with rust-prone parts staying rust-free for years. Ken Wild, Carwell's general manager, said that the company was also conducting trials with New York State testing T-32 on a steel bridge in Hamburg, New York.
Of course, if you're a private car owner and have only one, two, or even a dozen cars, it won't be cost effective for you to hire one of Carwell's fleet-targeted mobile service crews to travel to your location. Instead, you can buy the rust inhibitor and spraying tools from the company's website, which is what I did for my first couple of seasons as a well-armed soldier in the never-ending war against rust.
Even though applying rust inhibitor to my cars every year is a hassle (it takes at least 40 minutes for me to do a good job on one car, and even more if I have to drill access holes) it's a worthwhile headache. I park my cars outside, so they're constantly getting rained and snowed upon. Rust inhibitor, like WD-40, is, first and foremost, a water repellant. Spraying it inside body panels ensures that rust-causing moisture won't collect where I can't see it. Second, the process allows me a chance to get an intimate look at the car from all angles. If there are spots where the paint has chipped or gotten scratched, I make a note of it and apply touch-up paint (another great rust preventative) a few days later. As I'm treating door and body seams with rust inhibitor, I'm looking at the body's drain holes to make sure they're not clogged up. A clogged drain means water and dirt will collect where they're not supposed to.
If you decide to go the route I've taken and spray your own car, here's a recap on how it's done:
Suit up in clothing you don't mind getting dirty. T-32 is oily, and gets all over everything. Carwell recommends wearing a dust mask to keep vapor out of your nose and mouth. Safety glasses, although advisable, make it difficult to see when spray gets on them (if you get this stuff in your eyes, it blurs your vision until you blink the oiliness away, but it won't make you go blind or anything). Carwell's techs don't tend to wear glasses for this very reason.
Open the hood, tailgate, or trunk lid and all doors.
If necessary, drill small holes in the jamb side of each door, and in the door sills for access inside the door and rocker panels. Carwell recommends a 3/8-inch Irwin #12 step bit for the holes, and it supplies plastic plugs that fit perfectly into the holes. Try to avoid drilling into metal that's double layered, as it will be more difficult to drill through and harder to pop the plastic plugs into.
Use a long wand attachment to spray inside the doors and rocker panels. Keep spraying until you see "smoke" (atomized oil) begin to billow from gaps on the other side of the door, tailgate or panel you're working on. Spray the seams around all the doors and tailgate/trunk lid– Carwell says T-32 will creep between the seams once it's applied. Make sure to spray under the fuel cap access door if the car is equipped with one.
Spray inside the wheel wells. Make sure to get around the edges, and up where the shocks or struts are mounted.
Use a flexible hose attachment to spray inside the spaces inside the bottom of the hood, watching for smoke to emerge from the opposite ends of where you're spraying. There are many places for moisture to collect in there.
Spray around the sides of the engine compartment, between the radiator and the front clip and behind the lights. Don't worry about getting it on wires, as Carwell says it will seep beneath the wire casings to prevent corrosion. Be sure NOT to get it onto engine drive belts and tires, as it is very slippery and, as Tom Delavan, Carwell's fleet service manager, says, will "make the belts pop right off."
Pop plastic plugs into all of the access holes you have drilled. (Note: if you're working on a car that's rare or just don't want to drill holes in it, you can skip this step, or try to see if you can access the door cavity through the window slot or another hole. You can also remove the door trim panel.)
Raise the car and begin spraying the bottom. (If you're using jack stands, you should raise the car at the start of this whole process.) Start with all of the holes and crevices you can see—any place where moisture could hide. Move from the front to the back and systematically shoot every hole. Then, start back at the front and spray the entire bottom of the car, moving toward the back.
Wash the outside of the car to get rid of oily residue.
That's pretty much it. The car will drip T-32 for a few days, so it's probably not a good idea to park it in your garage or driveway. One of the school bus fleet managers from Upstate New York told me, however, that although dripping buses make a bit of a mess out of the school district parking lot, the stuff washes away after some wet weather sweeps through. (The parking lot at Carwell's own facility, which never gets a reprieve, is perpetually slippery). Wild said that T-32, according to regulation standards, "does not contain any solvents, known carcinogens, or hazardous materials."
To do all this yourself, you'll need an air compressor and some sort of spray gun. Delavan said a $20 paint sprayer from Harbor Freight Tools would work fine, but, naturally, recommended Carwell's more complicated (and accordingly more pricey, at nearly $500) five-gallon sprayer pot for more thorough application of T-32 to the insides of doors and rockers and inside cab corners and such.
To start, I shelled out about $200 for the one-quart spraying system Carwell makes for people with a vehicle or two and not much storage space, and a gallon of T-32. The custom-made door panel wands the sprayer came with worked well, and made it possible to get the rust inhibitor all the way inside the door without removing the trim panel. This year, however, Carwell sent me one of their five-gallon systems to try out, and although it's probably not something people with limited storage space would want to buy, it does a much more thorough job covering the large flat expanses on the undercarriage (it also operates at a higher pressure than the one-quart pot). I was able to spray several cars without putting much of a dent in the tank's five-gallon supply of T-32.
I'll be keeping tabs on how the state's trials at the Amsdell Road bridge in Hamburg turn out. If T-32 can save a structure that spends four months of the year covered in salt from rusting (and if my own cars continue to remain rust-free) it'll reinforce the fact that I've found a good thing.
But—and I can't stress this enough—the most important facet of rust prevention is to think of a vehicle's maintenance not just in terms of the engine, transmission and drivetrain, but of the body, too. If the oil is changed on a regular basis, it stands to reason that you would take steps to keep the body clean as well. If something mechanical breaks, you fix it to prevent larger problems down the road. Same thing goes with body damage. We can’t let the rust win, after all.