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Question DetailsAsked on 5/4/2013

should I rustproof my new vehicle

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From personal experience I would say definitely YES - but I personally would NOT get a professional job. They charge (especially dealers) hundreds of dollars for a 5 minute spot spray job. Even the "professional" ones like Dinol Tuffcoat and ZBart only do a hit and miss job from what I have seen, and commonly do not get the most likely to rust spots at all. Remember,the guys doing this are generally high school kids or the cheapest help they can get as technicians, so the level of attention to doing it right is low, and they are typically given only a half hour or so to do the entire job. Generally, most parts of new cars these days are pretty corrosion resistant, with a couple of exceptions. What I have done, and has pretty well eliminated body rust on our vehicles, is buy the do-it -yourself spray cans at NAPA and done it myself.

There is high-temp exhaust paint that you can spray on the muffler and tailpipe (including inside the end). Do NOT put on the header (pipes leading from the engine to the catalytic converter) or on or within 6 inches of the catalytic converter, as they rus way too hot and will set fire to the paint. These parts run hot enough they rarely rust out in less than 20+ years anyway, and are also so hot that they will cause the exhaust coating to catch fire and burn. Read instructions on the can for how far from cat converter to keep it, and be sure not to spray any on or close to wires or oxygen sensors sticking into the exhaust system. Just do the pipe leading away from the catalytic converter, the muffler, and the tailpipe. The newer the car when you do it the better, because you can just hose spray or wire brush it clean enough to apply the coating if you don't have enough miles on to have built up a heavy road dirt coating. The coating will stink pretty bad for the first 30 miles or so as it heats up and heat cures - but the smell will quickly go away as it heat-cures on the exhaust system. By the way, this is NOT part of a standard undercoat job, but can double the life of your exhust components, particularly the muffler and tailpipe which rust fastest because they are fully exposed to road mud and water, and run a lot cooler so condensation forms every time you start the car.

Exposed metal panels and frame you can spray with rubberized undercoating in a can, being careful to first mask your paint and plastic, rubber and moving parts with several layers of newspaper, as it will stick to and discolor your paint job, tires, and painted or plastic bumpers, so watch overspray. Do NOT get it on any moving or rubber parts like tires (including spare), wheel/hub area, driveline bearings, constant velocity joint rubber covers, universal joints, steering bearings, transmission linkage, engine, oil seals, etc. I would not worry about the differentials, transmission or transfer case - there are heavy enough metal they do not rust through, and are also generally leaky enough that they get an oil film on them that protects against rust.

Be careful to read the can for how far to keep it away from the exhaust system, and especially the cat converter and the area directly above and within about a foot of it. It is a rubberized asphaltic substance so it will catch fire if too close to heat sources. Do NOT coat the brake area, any wires or plastic or rubber parts, keep 3 inches or so away from oxygen sensors and any moving parts, and do NOT coat any heat shields mounted on or around the exhaust system (usually look like foil or stainless steel). Important places to hit that they typically do not do at the factory include the back or "inside" faces of bumpers (unless totally plastic) and associated mounting brackets, the inner face of rocker panels (panels under the doors) and quarter panels (panels around the wheels), metal wheelwells, metal gas tanks (avoid getting any on the filler/vent hoses, or the electrical comnponents going in the top), underslung spare tire carrier and area above the spare tire (do not get on the point where the spare tire clamps up against the frame, or on the spare tire or lowering cable or chain) and the frame and bumper mounting brackets, especially in the back 1/2 of the vehicle where it gets the most splash. Do NOT do the springs or shock absorbers. My preference is to hit all areas to be treated with a good coat of gray rustoleum clean metal primer first to enhance the rustproofing protection, then a day later put on the rustproofing spray. This not only provides an extra layer of reust protection, but using the gray primer then provides you a guide for the areas to be covererd with the black undercoating, which is hard to see on the usual black factory paint under the car - you just spray the undercoating till all the gray primer is covered.

There are videos on the web about places to be sure to hit and how to do it, and how to mask your paint and plastic so you don't ruin it. A proper job takes about 3-6 cans of the undercoater and 2-3 of the exhaust system coater, at about 10-15/can.

I personally do not worry about the inside of the door panels, partly becuause there is a lot of mechanism and electrical in there now that you can really mess up, and also because these areas are usually factory coated during assembly. The lower inside surface of the doors and the doorsill area within about 3 inches of the sill strip I do get though - takes a lot of masking and controlled spraying, but I do the door sill area and the bottom 6 inches or so of the door (the lower extension, horizontal part up to the vetical interior panel start). You have to leave the door open in 65 degree or higher temps for a good period of time (at least overnight, in a garage ?) or you can accelerate the drying with a hair dryer on low heat (bear in mind to keep back from the surface, as the drying fumes are flammable), and I tape some waxed paper to the contacting surfaces for a couple fo days so it does not stick closed. Also, during its drying time it will really ruin dresses, shoes, and pants of anyone getting in or out who rubs against the contact surface or bottom of the door, so this takes some close attention if you do this area, but it does cut down on the rust that forms in this area from wet feet getting in and out of the car over the years.

If you have removeable floor mats and can leave that area uncovered and unused for a few days while you use another car, you can do the area under the mats where water and snowmelt will accumulate and cause rusting. You have to let this dry severall days, and will stink the interior up a bit for a week or so, so you might want to drop back to just rustoleum in this area.

Remember to pull all tape and masking paper when you are done, ESPECIALLY around the exhaust system and engine - you don't want to accidentally set your car on fire.

Took me about 5 hours first time I did it - total (over 2 days) of about 2 hours the last time.

Answered 7 years ago by LCD

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