Vehicles in Ontario rust/corrode more than vehicles in other provinces in Canada. The reason is salt/calcium use by road maintenance agencies.
In Ontario new practices of pre-wetting the road salt to activate it quickly has begun due to new legislation against the use of salt. Salt use is scrutinized by environmental agencies, it is monitored, and municipalities can be fined or subsidies reduced if salt use is over the quota set out each year.
Part of this solution is to pre-wet salt with liquid calcium, this allows less salt to be used and it works faster for a longer period. Calcium is still corrosive to metals, but it is less scrutinized at this time. Sort of a workaround arrangement. They get the job done within the rules. Most municipal snow plow/spreaders now have GPS, they record the trucks route, amount of salt and the timeline for all salt dispensed. This is so Joe/Joan public cannot legally proceed with legal action if he should smash the mini van on the way to pick up Joannie/Johnny from flute lessons.
Salt/Calcium is a catalyst for rust, it will accelerate the electro/chemical reaction between metal and oxygen. Salt creates a better conductor for the process to begin and be successful. The metals on any vehicle will eventually rust/corrode. The items that make this process slow down are basic.
If the product has been engineered well, quality assurance has been a number one priority, all materials are treated with best industry practice coatings, such as zinc plating, use of stainless steel, all components in the structure allow air to dry the vehicle inside and out and assembly is best industry practice.
The vehicle should take an incredibly long time to corrode. Volvo cars have a great reputation in all the items I just mentioned. The most important item to keep your vehicle corrosion free is to keep the body as new. This is a loaded statement. Do not wax and polish each weekend, do not vacuum daily.
These things are okay if you have OCD (Obsessive Compulsive Disorder). Otherwise, you should read the owner’s manual. It may state to have the body and undercarriage inspected each year, preferably after winter. Most undercoating companies also demand a yearly inspection if you purchased the warranty with the undercoating. If you did not, they have no interest, except to put your cash in the till. A close friend has a body maintenance shop. He puts undercoating on vehicles when new (Dealers use his service), details cars and trucks. He wisdom on body maintenance is, "Keep it clean".
Most vehicles corrode in areas you do not see. They corrode at the bottom of the fenders, rocker panels, trunk bottom, front of the hood. Ever wonder why? Debris and stone chips.
Debris could be leaves that get washed down from the windshield hood area and cannot get out of the small drain holes at the fender, they accumulate and create a nice wet mess. The fenders usually rust inside out. Same with door bottoms, they all have drain holes at the bottom to let water out. They are often too small to let small plant seeds out, road sand, etc.
In freezing temperatures, water in the doors will freeze and can spread the crimped door panels and open the metal to the air. Perfect. Rocker panels, the section of the vehicle body below the doors is a good one. It is the lower structure of the vehicle cage. Most are sort of sealed, they should not be sealed at all. If they are sort of sealed, the factory corrosion inhibitor cannot properly attach, because it cannot be properly cleaned before hand, moisture cannot get out when you own the vehicle. Simple engineering. Well-engineered body sections have water drains, big ones.
Body maintenance is keeping the drains clear, in fenders, doors, rocker panels and touching up all stone chips on the panels, painted surfaces, and under the vehicle.
One of the most common component replacements at my shop, are engine oil pans. The engines do not leak oil any more, and the road debris sand blasts the metal engine oil pans and they rust through. Very expensive to repair. Many companies make the oil pans out of aluminum to add strength and longevity. Then the transmission pan corrodes away. Volvo has a shield under the engine to reduce/eliminate the road debris issue. Again, engineering.
So, does spray on undercoating work? does electronic corrosion protection work? Toss a coin. It will heavily depend on the product that you drive. Where you drive and how much you drive, if you park in a heated garage (very bad), If you have the body inspected each year, how the person inspects the body. The vehicles in Arizona corrode as well. Only because the paint is burnt off by the suns rays and the bare metal is exposed. They corrode on the top. Ours corrode on the bottom.
Most vehicle manufactures have a decent corrosion warranty, 5-7 years is normal. Most of us keep the car 5 years. The manufacturers know the game. Most corrosion warranties are not transferable. They know about the body maintenance game, your neglect is their gain. I have only been successful with police car warranty for corrosion and some oil pans. The floor pans rust out above the exhaust. We get them repaired at no charge because they all do it and the cars are 2-3 years old. Oil pans on some engines have a longer warranty and they replace them at the dealer. That is it. Pretty sad when you think about it
Meanwhile, the best bet, as my friend says, "Keep it clean".
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