Modern-day cars are corrosion protected straight from the factory, and there is truly no need for any additional corrosion treatments. A dealer might tell you otherwise, but all newer cars are rust protected. BMW for example offers a 12-year-long rust protection warranty.
Additionally, if you do decide to maximize the protection and opt for underbody coating, if the job is not done correctly it can even increase the chances of corrosion. Besides, if you are already getting warranted rust protection, doing any aftermarket protection might even void your warranty.
When you buy a car these days, dealers are offering you tons of different services like undercoating or different fabric protections. Most of these are just ways the salesman earns an additional dollar or two, and they are not all that necessary.
Undercoating a used car does make more sense, especially if the car is more than 10-15 years old. Adverse weather conditions, salt accumulation, how long do you plan to keep your car are all reasons to consider when talking about underbody coating.
Undercoating a new/used car
There are some benefits and drawbacks to undercoating a brand new car. The underbody of a new car is probably as clean as it ever will be, and this is a great time to apply rust protection. If you plan on keeping the car for decades to come, then go ahead and ask for undercoating to be applied.
If you want to undercoat a used car, there are lots of dirt and grime particles on the underbody of the car that are hard to clean out entirely. No matter how well you clean the car up, it will never be as clean as it was when it left the factory.
Different means of undercoating/rustproofing
There are lots of different undercoating/rustproofing techniques one can choose from. Whether it be a $120-150 drip/dripless/tar spray or a $500-1000 electronic module method, knowing the specifics of all these methods will help you decide which one is best for you.
The newest, most promising technology out of all of these is a strategically placed electronic module that sends a weak current throughout the car’s body panels which in theory should stop the metal from reacting with moisture and oxygen. This technology is still brand new though, and the reviews are rather mixed.
One of the most common ways of protecting your car from rust is undercoating. This technique consists out of spraying a tar-based solution onto all the exposed body panels. These types of coatings are usually applied to the undercarriage of the car, but they require a thorough application. If not done correctly, these can crack and moisture can get in.
Drip Oil Spray and Dripless Oil Spray are the two most common means of rust protection. The drip oil spray is probably a better idea because this technique is able to reach all the nooks and crevices more effectively, and the dripless one requires you to drill into specific body panels, and that is never a good idea.
Application and removal of rust protection
After you’ve considered all the options, you might even want to try the application process by yourself. You are going to need all the proper materials beforehand like a dedicated degreaser, lots of microfiber towels, dark automotive paint, brushes, undercoating material, undercoating remover material, grinder, primer, and lots of sandpaper.
You should start by thoroughly cleaning the car’s underbody. It is recommended that you use a hoist at this point. First, apply the degreaser and clean the surface, after that you should grind out all the visible rust spots if there are any. A dedicated pair of protection glasses are recommended. Sand any remaining rust with 220+ grit sandpaper.
Wipe away all the dust, prime out all the areas you’ve grinded, and paint all the primed areas with dedicated black automotive paint. Wait until the paint completely dries out and apply the undercoating to all the exposed areas. A rubberized undercoating solution is always a good idea because it protects the underbody a bit better.
It’s fairly easy to remove these types of undercoating solutions. All you have to do is buy a dedicated undercoating removal spray, spray it onto the surface, and wait until the undercoating starts softening up. At this point, you should just take a scraper and scrape all of the remaining coatings until you have a clean surface.
Which rustproofing technique is the best?
The best way of protecting your car from corrosion is through drip oil spray. The main benefits of this technique are primarily the price as it only costs $100-150 and the ease of application. Furthermore, this technique enables you to reach all the tight crevices without the need for any drilling or disassembly.
After you apply the drip oil can, it usually takes up to 48 hours for the coating to drip into all the designated areas. After this, the drip hardens and provides decent rust protection.
Should I apply the undercoating by myself?
It is recommended for you to leave it to a professional, but if you love working on your car you should give it a try. But be sure that you have all the necessary materials, especially all a hoist and a pair of eye protection glasses.
After you applied it, wait for a few days before taking the car for an inspection. It is always a good idea for an experienced professional to take a look at it, just to make sure that everything is as it should be.
How often should I undercoat my car?
Once you apply the undercoat, you also have to repeat this process at least once a year. And doing so is paramount because if you don’t, the older undercoating might ease off and let moisture in between the coat and the vulnerable areas which is a lot worse than no undercoating at all.
If you opt for a premium undercoating solution, a year is usually the timeframe, but many less expensive undercoating solutions only last a few months. So make sure that you are well informed about all the specifics of your desired undercoating solution.