Best Automotive Seam Sealer: Keep Your Vehicle Free of Rust and Drafts

Protect your vehicle from rust and corrosion with these automotive seam sealers

byAmy Poole, Nikola Petrovski|
Best Automotive Seam Sealer: Keep Your Vehicle Free of Rust and Drafts

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BYAmy Poole, Nikola Petrovski/ LAST UPDATED ON August 18, 2023

If you’ve noticed your car is beginning to develop rust, is in need of a body repair, or perhaps you feel a draft while driving, don’t contact your local garage just yet. There’s a quick and effective way to resolve this yourself without spending a lot of money.

Automotive body seam sealers are an inexpensive solution to these issues, and they come in a variety of options. For two figures, you can completely restore your vehicle and improve its longevity. Check out the best automotive seam sealers to protect your vehicle.

Best Overall

Eastwood Brushable Seam Sealer

This brushable product has excellent adhesion to prevent air and rain from entering your vehicle. Its flexible design means it won’t shrink surfaces, or harden or crack once it’s dried.
You can paint over the undercoating in 60 minutes. Waterproof and insulating features.
You need to purchase the brush separately. No nozzle for an easy application.
Best Value

3M Dynatron Auto Seam Sealer

3M Dynatron designed this sealer for a range of materials, including bare metal or painted surfaces. It blocks moisture to prevent corrosion and mold from forming.
Thick consistency to reduce drips when applying the product. Fast skinning begins after 10-15 minutes.
Not suitable for use in high temperatures. Doesn’t come with instructions, making it frustrating for novices.
Honorable Mention

ACDelco Auto Body Joint and Seam Filler

ACDelco is a non-sagging product that won’t crack or shrink after it’s applied. This water-resistant product is flexible and non-staining.
Provides excellent adhesive to a range of surfaces. An effective solution to leaks and cracks.
Avoid contact with  exhausts and catalytic converters. Tends to dry softer than competitive products.

Summary List

Types of Automotive Seam Sealers


Sealants come in a nozzle, so you can specifically apply the product to narrow areas, making them great for a touch-up job. Most sealants are transparent when they dry, so there’s no need to paint over the surface. This makes them a popular option for a quick-fix or sealing small cracks that are allowing air and water to enter.


A brushable seam sealer presents itself in a tin, which you apply to the surface using a paintbrush. This is an ideal option if you wish to target a large surface area without the hassle of applying a narrow tube across the entire area. As brushable sealers are designed for large areas—which is great as a body filler—they make a smooth, quick-drying base, making the surface paintable.

Best Automotive Seam Sealers: Reviews & Recommendations

This brushable product is ideal for adding anti-corrosion protection to your auto’s body if you want to target a large surface area. In less than 60 minutes, it’s completely dry, allowing you to paint on top to cover its gray finish.

Thanks to its waterproof and insulating features, this makes a great option for preventing cold air and rain from entering your vehicle. Plus, it prevents rust and corrosion from forming on your car in the first place.

Due to this type of product, you’ll need to purchase a brush separately, as it doesn’t come with tools. Plus, it dries a gray color, so you’ll need to paint over the result to match your auto’s body.

The 3M Dynatron heavy-duty product is permanently elastic and non-staining, making it ideal if you don’t plan to paint over the surfaces afterward. Apply it to gaps and voids in your vehicle—including the interior and exterior. It’ll reduce the chances of mildew and mold growth.

Its thick consistency makes this a great product to apply as it doesn’t produce any drips. Not all sealers are thick, which can make the application complex. It’s also reasonably priced. 

However, you should consider that the 3M Dynatron product doesn’t come with instructions or a long nozzle, which isn’t ideal for beginners or targeting hard-to-reach areas.

This ACDelco seam filler provides an excellent solution for sealing cracks, while providing a non-staining result that won’t crack. You can also paint over the finished surface just 60 minutes after you’ve applied the product.

It’s quick-drying and has a thick consistency, helping you to apply the solution without it pouring everywhere. Plus, it’s trust-worthy enough to use on panels that have been involved in a collision.

However, avoid using this seam filler near high-temperature objects, as it’s unsafe. Some customer reviews also report that it doesn’t dry as hard as competitor products.

This brushable seam sealer is fast-drying and designed for exclusive use on automobiles. You’ll like how this sealant remains flexible and won’t harden. This flexibility prevents cracking, sinking, and sagging. 

What’s nice about this 30.4 fluid ounce can is that it gives you excellent adhesion to the body while also filling seams, crevices, cracks, and joints. This sealant is waterproof and has insulating qualities. The color of this sealant is grey, and you can paint it in 30 to 60 minutes after application. 

Unfortunately, the consistency of this sealant is thick, requiring you to use a putty knife to apply it instead of an actual brush. The potentially messy application process and quick drying time make this sealant not first-timer friendly.

This one quart can of brushable seam sealer gives you plenty of sealant to work with. You can use it to spot-weld rivets, bolts, and joints. It will permanently adhere to painted and bare surfaces. What’s nice about this sealant is that it matches the OEM grey appearance and color for a clean finished product. 

It will skin over in 10 to 15 minutes and become a flexible and durable bond. After an hour, it will be dry enough to paint over. A nice-to-have quality is that this sealer is made to comply with strict standards for safety and efficiency. 

One downside of this seam sealer is that it comes in a quart can similar to a paint can. This can make it messy to use. You also don’t want to leave the can open for too long, or it will begin to skin over in the can.

Our Verdict

Our top recommendation is the Eastwood Brushable Seam Sealer. This reputable brand has experience in creating products to prevent rust from forming.

Alternatively, for a budget-friendly option, choose the 3M Dynatron Auto Seam Sealer. It’s compatible with a range of surfaces and easy to work with.

Benefits of Automotive Seam Sealers

  • Prolong the vehicle’s life. Using a high-quality seam sealer will prolong your vehicle’s lifespan after restoration. This is because most rust problems start in the seams.
  • Waterproof your car. If you’ve noticed drips of water entering your vehicle when it’s raining, these products will fill in any gaps, so no harsh winds or water can enter. Seam sealers are also resistant to motor oil.
  • Improve a paint job. Using a seam sealer before applying a new coat of paint can be essential to ensure all panels and joints are connected properly for a smooth, even finish.

Automotive Seam Sealer Pricing

  • Up to $20: The cheapest seam sealers will offer a waterproof feature and won’t crack once they’ve dried.
  • $20 and up: For the top-quality seam sealers, you can expect a quick-drying action, plus insulating features to prevent the inside of your car from getting cold. These will also likely come with different sized nozzles for a convenient application.

Key Features

Water- and Corrosion-Proof

One of the biggest features of this type of product is that they’re water- and corrosion-proof. This creates a protective layer on your vehicle—whether that’s on the interior or exterior—to prevent weather from eroding your car. 

Compatible With a Range of Materials

Thanks to the versatility that seam sealers offer, most are compatible with numerous materials,  including metal, chrome, and plastic. This feature allows you to use the product on a range of surfaces in your vehicle, from under the hood to plastic components on the dashboard.

No Shrinkage

As sealers are designed for a range of surfaces and components in your vehicle, one of their key features is not shrinking the materials. Otherwise, the surfaces would pull apart once the sealer has dried. Plus, the sealer won’t crack once the application is complete.

Other Considerations

  • High Temperature Rating. If you plan to use the seam sealer around the engine, you’ll require a product that has a high temperature rating. Ensure it can operate on surfaces up to 450 degrees Fahrenheit.
  • Long-Reach Applicator. The applicator’s design can make a huge difference in terms of convenience and ease. Opt for a sealer with a long-reach design that allows you to target deep into the hood without putting your arm far in.
  • Transparency. This isn’t essential for everyone, as it depends on whether you wish to paint the surface once the sealer has dried. Check the product descriptions to learn what the finish looks like.


  • The surface you apply the sealer must be clean, dry, and free from grease.
  • Most products don’t allow you to paint over them immediately, so check the instructions. You may have to wait for the sealer to dry overnight. 
  • Always follow safety instructions when applying the sealer. Most require you to wear protective gear so you don’t inhale fumes.


Q: How often should you replace your car’s sealant?

A: We recommend monitoring your vehicle’s rust patches. If you notice them forming, be proactive and purchase a seam sealer. Alternatively, replacements every five years or so should keep this issue from arising.

Q: Can you use a silicone sealant on your vehicle?

A: No. You can’t paint over silicone, which will leave your vehicle looking unpresentable. More importantly, it takes a lot of preparation before applying the product and doesn’t provide a long-lasting effect. 

Q: Are all seam sealers the same?

A: Most seam sealers have similar qualities, though they’re not all the same. Some leave a smoother surface, while others need more preparation before painting on them. 

Why Trust Us

Our reviews are driven by a combination of hands-on testing, expert input, “wisdom of the crowd” assessments from actual buyers, and our own expertise. We always aim to offer genuine, accurate guides to help you find the best picks.

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