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Caring for Aluminum Body Panels and Wheels

Automakers are increasingly turning to aluminum to reduce weight and improve fuel economy. However, this metal’s use isn’t new. From Land Rovers to sports cars, aluminum has always been the choice for designers looking to remove weight and reduce corrosion. Here’s what you need to know to take care of the aluminum parts of your car.

Is My Car Made of Aluminum?

For those of us who aren’t auto enthusiasts, aluminum body panels may seem like a new development. Ford switched to aluminum body panels on their F-150 in 2015, and other companies are following suit with their full-size trucks. Meanwhile, cars, crossovers, and SUVs are increasingly using the metal for some of their body panels. However, aluminum is not new to the auto industry. Land Rover has used aluminum body panels since they started production in the 1940s. In the past 20 years, automakers have used aluminum for doors, trunks, and hoods to reduce weight.

In most cases, you can tell if a panel is aluminum by checking it with a magnet. However, an aluminum truck or van door may have steel under the sheet metal for magnetic signs.

Even if a vehicle has an all-aluminum body, it still has some steel components. That means if you skip the rust protection on your F-150, the outside will be fine, but the frame will still rust.

Can Aluminum Rust?

Iron and aluminum can both oxidize. However, the results are different depending on the metal.

Steel body panels contain iron, which reacts with oxygen to form iron oxide. This is what we call rust. Saltwater acts as a catalyst, speeding up the process. That’s why cars driven on salt-covered roads in the winter rust faster than cars in snow-free areas. Red rust, AKA ferric oxide, has larger molecules than those found in steel. As a result, this rust expands as it’s formed, weakening the panel’s structure and eventually flaking off.

Aluminum will bond with oxygen, forming aluminum oxide. However, while iron oxide will spread, aluminum oxide forms a hard, protective layer over the part. That means it won’t rot away like a steel panel, but that oxide layer can cause the paint to separate from the panel. The panel may look bad, but it will mostly hold together.

Aluminum is subject to galvanic corrosion. In this process, an anode (aluminum) transfers electrons to a cathode (steel) through an electrolyte (saltwater). This creates aluminum ions, weakening the part. Manufacturers prevent this by electrically isolating steel and aluminum components. This may be as simple as painting the parts or using insulators to keep them separate. Quality collision repair is important to keep these parts from touching. The repair may look correct on the outside, but if the shop used steel rivets in place of aluminum ones or seam sealer in place of glue, you could end up with corrosion down the road.

Paint Care

While the primer may use a different formula to adhere to aluminum, the top coats are identical to those used on steel panels. That means you can take the same steps to take care of your car’s paint.

Caring for Aluminum Wheels

Even if your car is all steel, it may have aluminum alloy wheels. These wheels are subject to the same problems as aluminum body panels.

Keeping your wheels clean is critical if you want to keep them looking nice. Brake dust is highly corrosive and can pit aluminum if it’s left on the wheel. When you wash the wheel, use a non-acidic wheel cleaner made specifically for aluminum wheels. If the wheel still looks dull, use a clay bar. The bar will lift out embedded dirt just like it does when cleaning paint.

Most factory wheels have a layer of clearcoat, while aftermarket wheels, particularly those marketed for use on classic cars, have exposed metal. Make sure you know which type you have before trying to polish your wheel. Aluminum wheel polish can damage clearcoat.

No Matter What You Drive, We Can Help You Get it Back on the Road

Merton Auto Body has been in the auto body repair business for over 70 years, growing with the changes in automotive technology. If you need to have your car fixed after an accident, go with the shop trusted by people across Lake Country. Our shop is just up the road from Ironwood Golf Course, just a few miles from Pewaukee, Lisbon, Sussex, and North Lake.